JPH11230520A - Direct melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct melting furnace which enables smooth and stable treatment of waste while facilitating adaptation to growing size without causing any substantial change in the temperature and the pressure in a furnace. SOLUTION: In this vertical type shaft kiln, a waste dumping port is provided at an upper part or a side body part thereof, an introduction pipe of a gas containing oxygen is connected to a side wall of a bottom part thereof so that zones for drying, thermal decomposition and combustion and melting are formed sequentially inside downward from the waste dumping port and a removal port of a molten slag is formed at the lower end thereof. It is so arranged in terms of the dimension of a sectional area that the bottom part 23 forming the combustion/melting zone 22 supports a waste 24 at the central part of a bottom surface 25 while a dome by the waste 24 is formed at the outer circumference part facing a jetting port of an introduction pipe 28 at the central part of the bottom surface 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct melting furnace used when slagging wastes using a gasification and melting technique.

[0002]

2. Description of the Related Art In recent years, in order to treat general waste including garbage and the like and industrial waste including sludge and the like, waste treatment facilities using various gasification and melting processes have been developed. The department is being put into practical use. FIG.
1 shows a vertical shaft furnace 1 constituting a main part of a conventional processing facility of this kind as seen in Japanese Patent Publication No. 51-42434. The vertical shaft furnace 1 has a bottomed cylindrical shape whose inner wall is made of a refractory material, and has an inlet 2 for introducing pulverized waste into an upper side wall thereof. The vertical shaft furnace 1 is formed so that the inner diameter gradually increases downward from the input port 2, and the bottom 1 a of the vertical shaft furnace 1 gradually decreases downward from the maximum inner diameter part 4. Is formed. The reduced-diameter bottom portion 1a of the vertical shaft furnace 1 is supplied with oxygen-enriched air to a char obtained by pyrolysis of waste to maintain the inside at a high temperature. Introductory pipe 3
Is connected to the furnace bottom, and a slag discharge port 5 for discharging the molten and solidified product generated in the vertical shaft furnace 1 is formed in the furnace bottom. On the other hand, a gas combustion furnace (not shown) for completely burning the pyrolysis gas in the reducing atmosphere generated by the pyrolysis of the waste is disposed above the vertical shaft furnace 1.

[0003] In the vertical shaft furnace 1 having the above-described structure, first, crushed waste or a secondary material such as coke is added to the waste and the vertical shaft furnace 1 is introduced through the charging hole 2.
The waste is dried in the upper drying zone 6 and then pyrolyzed in the lower pyrolysis zone 7 to generate pyrolysis gas and carbonaceous and high-calorie char. . This char travels further down the furnace, forming a dense dome 10 in the slope 9 below the largest inner diameter 4 below the pyrolysis zone 7. Then, the char reacts with the oxygen-enriched air and / or preheated air supplied from the introduction pipe 3, so that 1600 ° C. is formed below the dome 10 of the vertical shaft furnace 1.
Combustion / melting zone 8 maintained at a high temperature of about 1800 ° C
Is formed. The heat in the combustion / melting zone 8 causes the non-flammable components in the waste to become harmless molten slag (vitreous molten material), and dripping along the inclined portion 9 and the reduced diameter side wall 11. Then, it is continuously discharged from the slag discharge port 5. At the same time, the high-temperature gas generated in the combustion / melting zone 8 rises in the furnace and thermally decomposes the waste sequentially charged in the pyrolysis zone 7 to become a pyrolysis gas in a reducing atmosphere. ,
Further, the waste just introduced from the introduction hole 2 in the drying zone 6 is dried by the pyrolysis gas.

[0004] In such a vertical shaft furnace 1, waste is pyrolyzed in the vertical shaft furnace 1 to obtain a pyrolysis gas and a carbonaceous high-calorie char. And / or supply preheated air to discharge non-flammable components in waste as harmless molten slag to the outside of the system. The large volume reduction rate minimizes landfill disposal and enables high-temperature melting. The treated slag has the advantage that no heavy metals are eluted and that it can be reused.

[0005]

In such a conventional vertical shaft furnace 1, in order to smoothly perform a series of operations such as the above-described waste input, drying, pyrolysis, and combustion / melting, A solid dome 10 made of char and non-combustible components is always formed in a stable state below the pyrolysis zone 7 to prevent the waste from moving to the combustion / melting zone 8, thereby preventing the waste from moving to the dome 10. The upper char is effectively burned by the hollow combustion / melting zone 8 formed in the above, and by constantly maintaining the combustion / melting zone 8 at a high temperature, the non-combustible component in the upper waste is melted. It is desirable that the generated molten slag is continuously discharged from the slag discharge port 5.

However, in the conventional vertical shaft furnace 1 described above, the dome 10 is provided with the inclined portion 9 having a reduced diameter.
When the amount of waste accumulated in the furnace and the input amount of oxygen-enriched gas or preheated air fluctuate,
The construction position of the dome 10 changes. As a result, the dome 10 becomes unstable, and the furnace temperature and the furnace pressure fluctuate, so that there is a problem that it is difficult to perform a smooth waste disposal. In particular, in response to a demand for a large-scale waste treatment facility in recent years, by increasing the inner diameter of the vertical shaft furnace 1, a large amount of waste is to be treated by one vertical shaft furnace 1.
The formed dome 10 also has a problem that the diameter of the dome 10 becomes too large to strongly support the waste above, and this has been a major factor in preventing the waste treatment facility from being enlarged.

In the vertical shaft furnace 1 described above,
Since the molten slag generated in the combustion / melting zone 8 kept at a high temperature drops from the inclined surface 9 of the combustion / melting zone 8 along the side wall 11, the molten slag is dropped and the inclined surface 9 and the side wall 11 are dropped. Is severely damaged by the refractories, and as a result, the service life generally expires every few months, and the refractories constituting the inclined surfaces 9 and the side walls 11 must be replaced.

SUMMARY OF THE INVENTION The present invention has been made to effectively solve the problems of the conventional direct melting furnace described above, and is capable of smoothly and stably disposing waste without causing large fluctuations in furnace temperature and furnace pressure. It is an object of the present invention to provide a direct melting furnace that can perform a process and can easily cope with an increase in size.

[0009]

According to the first aspect of the present invention, there is provided a direct melting furnace according to the present invention, wherein a waste inlet is provided at an upper portion or a side body portion, and an oxygen-containing gas inlet pipe is connected to a bottom side wall. In this way, a vertical shaft furnace in which zones for drying, pyrolysis and combustion / melting are sequentially formed downward from the above-mentioned inlet, and an outlet for molten slag is formed at the lower end. And the bottom where the combustion / melting zone is formed supports the waste at the center of the bottom surface,
The cross-sectional area is such that the dome of the waste is formed from the center of the bottom surface to the outer peripheral portion facing the outlet of the introduction pipe.

[0010] According to a second aspect of the present invention, the bottom has a cross-sectional area of 7/1 of the cross-sectional area in the pyrolysis zone.
It is characterized by being 0 or more, and the invention according to claim 3 is characterized in that a weir is provided at the molten slag discharge port. Further, the invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein a groove is formed on an outer peripheral portion of a bottom surface on which the molten slag flows down. . The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein at least the bottom portion is
It is characterized by being square.

In the direct melting furnace according to any one of the first to fifth aspects, the waste is supported at the center of the bottom surface, and faces the outlet of the introduction pipe from the center of the bottom surface toward the bottom side wall. A strong dense layer dome is formed. And this dome, around each inlet pipe at the bottom,
Alternatively, since it is formed continuously along the outer circumference, the total length of the legs is significantly longer than in the past, and the amount of upper waste to be supported per unit area is significantly reduced. Become stable. As a result, even if the amount of accumulated waste in the furnace or the amount of the combustion supporting gas charged changes, the dome is not destroyed, so that the fluctuations in the furnace temperature and the furnace pressure due to this do not occur. It is possible to avoid the generation of the waste gas and stably perform the gasification and melting treatment of the waste over a long period of time, and it is possible to easily cope with an increase in the size of the entire waste treatment apparatus.

Further, the waste burned and melted in the combustion / melting zone at the bottom becomes molten slag, flows down to the bottom surface along the side wall of the dome, and is discharged from the molten slag discharge port. As a result, since the molten slag does not flow down the furnace wall as in the conventional case, erosion of the furnace wall refractory material caused by the flow of the molten slag can be prevented, and its durability is markedly improved. Can be improved. In order to form the bottom so that the waste is supported at the center of the bottom, the cross-sectional area should be 7/10 or more of the cross-sectional area in the pyrolysis zone. It is more preferable to form it into a straight body having the same shape as the thermal decomposition zone. That is, if the bottom is formed by reducing the cross-sectional area to less than 7/10 of the cross-sectional area in the pyrolysis zone, the outer shape from the lower portion of the pyrolysis zone to the combustion / melting zone is reduced as in the related art. This is because an unstable dome similar to that shown in FIG. 4 is formed using the portion thus set as a leg.

According to the third aspect of the present invention, if a weir is provided at the molten slag discharge port, the molten slag can stay at the bottom for a certain period of time. As a result, the molten slag can be homogenized. If a groove is formed in the outer peripheral portion of the bottom surface on which the molten slag flows down as in the invention according to claim 4, the amount of retained molten slag increases. It is possible to further improve the homogenization effect of the molten slag.

Then, as in the invention according to claim 5,
If the bottom is formed in a square shape, the dome can be formed along the flat side wall, so that the length of the side wall is appropriately set according to the scale of the waste disposal facility. Accordingly, it is possible to increase the size of the entire waste disposal apparatus by using the same design standard.

[0015]

1 and 2 show a main part of a direct melting furnace according to a first embodiment of the present invention. As shown in FIG. 1 and FIG.
Is a vertical shaft furnace which is formed in the shape of a bottomed rectangular tube as a whole, and has a horizontal cross-sectional dimension from a portion where the pyrolysis zone 21 is formed to a lower bottom portion 23 where the combustion / melting zone 22 is formed. It is formed in a certain straight body shape. This allows
When the waste 24 is gasified and melted in the direct melting furnace 20, the waste 24 is supported at the center of the bottom surface 25.

On the outer periphery of the lower end of the bottom 23,
A molten slag discharge port 26 is formed, and a weir 27 is formed between the bottom surface 25 and the molten slag discharge port 26. In addition, on the side wall of the bottom portion 23, a nozzle (introduction tube) 28 for introducing an oxygen-enriched gas or preheated air (oxygen-containing gas) is provided.
Is attached. The injection nozzle 28 is provided at the bottom 2
3 are attached at predetermined intervals toward the above-mentioned longitudinal direction, respectively. As a result, a dome 29 made of the char and non-combustible components generated by the decomposition of the waste 24 is formed on the outer peripheral portion of the bottom portion 23 where the combustion / melting zone 22 is formed, facing the ejection port of the charging nozzle 28. It is supposed to be.

In the direct melting furnace 20 having the above-described structure, the bottom portion 23 is formed in the same cross-sectional shape as the upper portion where the pyrolysis zone 21 is formed.
5 support a waste 24 at the center and a bottom 25
A dome 29 of a strong dense layer facing the ejection opening of the injection nozzle 28 is formed from the center of the dome toward the side wall of the bottom 23. Since the dome 29 is formed continuously along the longitudinal side wall of the bottom portion 23 as shown in FIG. 2, the total length of the leg portion is significantly longer than that of the related art. It is extremely stable because the amount of upper waste 24 to be supported per area is significantly reduced.
As a result, even if the accumulated amount of the waste 24 in the furnace or the amount of the combustion supporting gas charged from the charging nozzle 28 changes, the dome 29 is not destroyed, and the furnace temperature caused by the dome 29 does not change. And the occurrence of fluctuations in the furnace pressure are avoided. Further, even if a sudden change in operating conditions occurs, only a part of the dome 29 is destroyed, so that there is no danger of a large fluctuation in the furnace temperature and pressure.

Then, the molten slag generated in the combustion / melting zone of the bottom portion 23 travels along the side wall of the dome 29 and passes through the bottom surface 2.
After flowing down onto the slag 5 and staying for a certain amount, it overflows from the weir portion 27 and is discharged to the molten slag discharge port 26.
As a result, since the molten slag does not flow down the furnace wall as in the conventional case, erosion of the furnace wall refractory material caused by the flow of the molten slag can be prevented, and its durability is markedly improved. Can be improved. Further, since the weir portion 27 is provided at the molten slag discharge port 26, the molten slag can stay at the bottom 25 for a certain period of time, so that the molten slag can be homogenized.

Therefore, according to the direct melting furnace 20, stable gasification and melting of the waste 24 can be performed over a long period of time, and the whole including the bottom portion 23 is formed in a square shape. Therefore, the dome 29 can be formed along the flat side wall, and accordingly, by appropriately setting the length of the side wall in accordance with the scale of the waste treatment facility, the same design standard can be used. The size of the entire waste disposal apparatus can be increased.

FIG. 3 shows a modification of the embodiment shown in FIGS. 1 and 2. The same components as those shown in FIGS. Omitted. In the direct melting furnace 30 shown in FIG. 3, grooves 31 are formed on both outer peripheral portions of the bottom surface 25 where the molten slag flows down along the longitudinal direction. Thereby, the dome 2
The molten slag flowing down to the groove 31 of the bottom surface 25 along 9 is taken out from the weir 27 to the outlet 26.

In this direct melting furnace 30, the same operation and effects as those shown in FIGS. 1 and 2 can be obtained, and the separation of waste and molten slag is further improved. Since the amount of retained molten slag in the bottom 25 is increased by the grooves 31 formed on the outer periphery of the slag, an effect that the effect of homogenizing the molten slag can be further improved is obtained.

In each of the above embodiments, only the case where the direct melting furnaces 20 and 30 are formed in a square shape as the most preferable form has been described. However, the present invention is not limited to this. The present invention can be similarly applied to a direct melting furnace having a shape similar to that described above. The inner diameter may be used.

[0023]

As described above, according to the direct melting furnace according to any one of the first to fifth aspects of the present invention, the waste is supported at the center of the bottom surface, and from the center of the bottom surface. Since a dome of a strong dense layer is formed facing the outlet of the introduction pipe toward the bottom side wall, the dome does not change even if the amount of accumulated waste in the furnace or the input amount of the combustion supporting gas changes. Is not destroyed, so that fluctuations in the furnace temperature and the furnace pressure due to this are avoided, so that stable gasification and melting of waste can be performed over a long period of time. It is possible to easily cope with an increase in the size of the entire material processing apparatus. further,
The waste combusted and melted in the combustion and melting zone at the bottom becomes molten slag, flows down to the bottom surface along the side wall of the dome, and is discharged from the molten slag discharge port.
As a result, since the molten slag does not flow down the furnace wall as in the conventional case, erosion of the furnace wall refractory material caused by the flow of the molten slag can be prevented, and its durability is markedly improved. Can be improved.

In particular, according to the third aspect of the invention, the molten slag is allowed to stay at the bottom for a certain period of time, thereby making it possible to homogenize the molten slag. According to this, since the amount of retained molten slag increases, it is possible to further improve the homogenizing effect of the molten slag described above. Further, when the bottom is formed in a square shape as in the invention according to claim 5, the length of the side wall is appropriately set in accordance with the scale of the waste treatment facility, thereby achieving the same design standard. As a result, it is possible to increase the size of the entire waste disposal apparatus.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing a first embodiment of a direct melting furnace according to the present invention.

FIG. 2 is a schematic perspective view showing a dome shape of the embodiment shown in FIG.

FIG. 3 is a longitudinal sectional view of a main part showing a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a conventional vertical shaft furnace.

[Explanation of symbols]

 2 Input port 6 Drying zone 20, 30 Direct melting furnace 21 Pyrolysis zone 22 Combustion / melting zone 23 Bottom 24 Waste 25 Bottom 26 Molten slag outlet 27 Weir 28 Input nozzle (oxygen-containing gas inlet pipe) 29 Dome 31 Groove

Claims (5)

[Claims] 1. A waste inlet is provided at an upper or side body portion, and an inlet pipe for oxygen-containing gas is connected to a bottom side wall. A vertical shaft furnace in which each zone of pyrolysis and combustion / melting is formed, and a discharge port of molten slag is formed at the lower end, and the bottom where the combustion / melting zone is formed is a bottom surface center. Direct melting characterized in that it has a cross-sectional dimension such that a dome of the waste is formed from the center of the bottom surface toward the outer peripheral portion facing the spout of the introduction pipe from the bottom center. Furnace. 2. The direct melting furnace according to claim 1, wherein a cross-sectional area of the bottom is at least 7/10 of a cross-sectional area in the pyrolysis zone. 3. The direct melting furnace according to claim 1, wherein a weir portion is provided at the discharge port. 4. The direct melting furnace according to claim 1, wherein a groove is formed in an outer peripheral portion of the bottom surface on which the molten slag flows down. 5. The direct melting furnace according to claim 1, wherein at least the bottom is rectangular.