JPH11159724A - Direct melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a direct melting furnace which can stably perform gasifying melting treatment on rubbish by always forming a dome of a firm compact layer in the lower section of a thermally decomposing zone. SOLUTION: A direct melting furnace is constituted in a vertical shaft furnace in which a drying zone, a thermally decomposing zone 21, and a burning and melting zone 23 are successively formed toward the bottom of the furnace from a rubbish throwing-in port by providing the charge port through the top or side wall section of the furnace and connecting an oxygen-containing gas introducing pipe 25 to the bottom section of the furnace. In the furnace, the bottom section 22 where the burning and melting zone 23 is formed has a cross- sectional area smaller than that of the overlying thermally decomposing zone 21 and, a large shelf section 27 which is inclined from the plumb line at a large angle is formed between the bottom section 22 and the lower section of the thermally decomposing zone 21.

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 municipal waste including garbage, general waste including sludge, and industrial waste,
Waste treatment facilities using various gasification and melting processes are used. FIG. 7 shows a vertical shaft furnace 1 which constitutes a main part of this type of conventional processing equipment as disclosed in JP-B-51-42434. This vertical shaft furnace 1
Has an inner wall made of a refractory material and has a bottomed cylindrical shape, and an inlet 2 for introducing crushed waste is provided in an upper side wall thereof. This vertical shaft furnace 1
The inner diameter is formed so as to gradually increase downward from the inlet 2, and the bottom 1 a is formed so as to gradually reduce the diameter downward from the maximum inner diameter part 4. Then, the reduced diameter bottom portion 1 of this vertical shaft furnace 1
a, an oxygen-enriched air introducing pipe 3 for supplying oxygen-enriched air to the char obtained by pyrolysis of waste to maintain the inside at a high temperature is connected to the furnace. A slag discharge port 5 for discharging the molten solid generated in the vertical shaft furnace 1 is formed. 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.

In the vertical shaft furnace 1 having the above structure, first, crushed waste is put into the vertical shaft furnace 1 through the charging hole 2, and the waste is put into the upper drying zone 6.
And then pyrolyzed in the lower pyrolysis zone 7 to generate pyrolysis gas and carbonaceous, 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 1 char is formed below the dome 10 of the vertical shaft furnace 1.
A combustion / melting zone 8 maintained at a high temperature of about 600 ° C. is formed. The heat in the combustion / melting zone 8 causes the incombustibles in the waste to become harmless molten solids (vitreous melts), and drops along the inclined portion 9 and the reduced diameter bottom 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 ascends 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 input from the input hole 2 in the drying zone 6 is dried by the pyrolysis gas.

[0004] In such a vertical shaft furnace 1, waste is thermally decomposed in the vertical shaft furnace 1 to obtain a combustion exhaust gas and a carbonaceous, high-calorie char. Alternatively, it supplies preheated air and discharges incombustibles in the waste as harmless molten slag outside the system. Slag has the advantage that no heavy metal is eluted and 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 stable dome 10 is always formed below the pyrolysis zone 7 to prevent the waste from moving to the combustion / melting zone 8, whereby the hollow combustion / melting zone 8 formed below the dome 10 is formed. By burning the upper char effectively, and always keeping the combustion / melting zone 8 at a high temperature, incombustibles in the upper waste are burned / melted and continuously discharged from the slag discharge port 5. It is desirable to go.

However, in the conventional vertical shaft furnace 1, the dome 10 is constructed on the inclined portion 9 of the reduced diameter portion where no clear sectional area division is formed, so that the inside of the furnace is not provided. If the amount of waste accumulated or the amount of oxygen-enriched gas or preheated air charged fluctuates, the construction position of the dome 10 will change. As a result, the dome 10
Becomes unstable, and the furnace temperature and the furnace pressure fluctuate, which makes it difficult to perform a smooth waste disposal.

Accordingly, a support such as a water-cooled grate is provided below the pyrolysis zone 7, and the dome 10 is placed on the support.
It has also been proposed to form However, when the above-mentioned support is constructed, the support bears the entire weight of the waste and is further exposed to the high temperature of 1600 ° C. or more from the combustion / melting zone 8,
There is a problem in that continuous operation is restricted because the strength is deteriorated with time and repair and replacement are required in a short period of time. In addition, if the support is broken, the operation is forcibly stopped, and the vertical shaft furnace 1 is seriously damaged.

In the vertical shaft furnace 1 described above,
Since the molten solid generated in the combustion / melting zone 8 kept at a high temperature drops along the side wall 11 from the inclined surface 9 of the combustion / melting zone 8, the inclined solid 9 is dropped by the dripping of the molten solid. The problem is that the refractory constituting the side wall 11 is severely eroded and, as a result, its life generally ends every one to several months, and the refractory constituting the inclined surface 9 and the side wall 11 must be replaced. was there.

The present invention has been made in order to effectively solve the above-mentioned problems of the conventional direct melting furnace, and it is possible to always form a dome of a strong dense layer at the lower part of the pyrolysis zone, so that a stable dome can be obtained. It is an object of the present invention to provide a direct melting furnace capable of performing gasification and melting treatment of waste.

[0010]

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 or side body, and an oxygen-containing gas inlet pipe is connected to a bottom. A vertical shaft furnace in which zones for drying, pyrolysis, and combustion / melting are sequentially formed downward from the input port, and a bottom portion in which the combustion / melting zone is formed. Is formed such that its cross-sectional area is smaller than the cross-sectional area in the upper pyrolysis zone,
A shelf is formed between the bottom and a lower portion of the pyrolysis zone, the shelf having a larger inclination angle with respect to a vertical line than the bottom.

Here, in the invention according to claim 2, the bottom part according to claim 1 is a straight body part, and the sectional area of the bottom part is 1/10 to 7 of the sectional area in the pyrolysis zone.
In a third aspect of the present invention, the shelf portion is formed by a plurality of inclined surfaces whose inclination angles with respect to the vertical line gradually increase from above to below. It is characterized by having.

The invention described in claim 4 is the first invention.
The portion where the thermal decomposition zone is formed according to any one of (1) to (3), is characterized in that its cross-sectional area is formed so as to gradually increase from above to below. The invention according to claim 5 is characterized in that the bottom side wall according to any one of claims 1 to 4 is formed of a metal material into which a cooling medium is introduced. .

[0013] In the direct melting furnace according to any one of claims 1 to 5, between the pyrolysis zone and the combustion / melting zone,
A ledge is formed whose inclination angle is more horizontal than the bottom where the combustion / melting zone is formed. Using this shelf as a leg, a stable and strong dense layer dome is formed that does not depend on the amount of accumulated waste in the furnace or the amount of oxygen-containing gas such as oxygen-enriched gas or preheated air. Is done. As a result, it is avoided that the dome is destroyed as in the conventional case and the fluctuations in the furnace temperature and the furnace pressure due to this are caused. Can do it.

Here, as in the invention described in claim 2,
The bottom is formed in a straight body, and the cross-sectional area of the bottom is 1/10 to 7/1 of the cross-sectional area in the pyrolysis zone.
If it is set in the range of 0, since a place where the sectional area is clearly narrowed is formed between the straight body and the shelf, a more stable and strong dome is formed using the place as a leg. It is preferable that it can be formed. In addition, as the above-mentioned shelf,
Although it is also possible to form by one inclined surface, for example, as in the invention of claim 3, if it is formed by a plurality of inclined surfaces in which the inclination angle with respect to the vertical line increases gradually from above to below, The effect is obtained that the inclined surface near the connection with the combustion / melting zone becomes more horizontal, and the effect of forming the dome is improved.

Further, in the invention according to claim 4,
Since the section where the pyrolysis zone is formed is formed so that its cross-sectional area gradually increases from above to below,
The downward movement of waste from the drying zone is not hindered by the side walls where the pyrolysis zone is formed,
It is possible to promote smooth waste transfer. Furthermore, if the bottom side wall where the combustion / melting zone is formed is made of a metal material into which a cooling medium is introduced, the molten solid generated by the high-temperature heat in the combustion / melting zone Since the object solidifies on the surface of the metal material and functions as a heat insulating layer, the surface of the metal material can be protected, and therefore, the durability is remarkably longer than the conventional case where the side wall is made of a refractory. Performance can be improved.

[0016]

FIG. 1 shows a main part of an embodiment of a direct melting furnace according to the present invention, and the upper structure is the same as that shown in FIG. As shown in FIG. 1, the direct melting furnace 20 is a vertical shaft furnace formed in a substantially cylindrical shape as a whole, and a pyrolysis zone 21 having an upper diameter is provided at a bottom portion below the pyrolysis zone 21. A straight body portion 22 smaller than the diameter of the portion to be formed is provided.
A combustion / melt region 23 is formed therein. Here, the diameter of the straight body portion 22 is set in the range of 1/10 to 7/10 of the diameter in the pyrolysis zone 21, and in this embodiment, 4/10 to 6/10.

The straight body portion 22 is formed of a metal material having excellent heat conductivity, for example, a copper casting, and is hollow so that the inside thereof is cooled by cooling water supplied from a cooling water pipe (not shown). It has become. Further, a molten slag discharge port 24 is formed integrally with the outer periphery of the lower end of the straight body portion 22. Furthermore, in the lower part of the straight body part 22,
An injection nozzle (introduction pipe) 25 for oxygen-enriched gas or preheated air (oxygen-containing gas) is attached so as to jet the flame toward the center of the furnace bottom 26. A shelf 27 is formed between the straight body 22 and the lower part of the pyrolysis zone 21. Here, the shelf 27 is formed by two inclined surfaces 28 and 29 whose inclination angles with respect to the vertical line increase gradually from above to below.

In the direct melting furnace 20 having the above-described structure, the inclination angle with respect to the vertical line from the upper part to the lower part between the pyrolysis zone 21 and the combustion / melt region 23 formed by the straight body portion 22. Two slopes 2 where
Since the shelf 27 composed of 8 and 29 is formed, the inclined surface 29 of the shelf 27 has a nearly horizontal inclination angle.
As a result, a portion where the cross-sectional area is clearly narrowed is formed at the connection portion between the inclined surface 29 and the straight body portion 22, and the accumulated amount of waste in the furnace and ,
A stable and strong dense layer dome 30 is formed that does not depend on the amount of oxygen-containing gas such as oxygen-enriched gas or preheated air. Then, the dome 30 is stably formed, thereby preventing the waste from moving to the combustion / melt region 23, and thereby the hollow combustion / melt region 23 formed below the dome 30 causes the waste to move upward. Is effectively burned, and the combustion / melting zone 8 is always kept at a high temperature, so that the incombustibles in the upper waste are burned / melted and sequentially discharged from the slag discharge port 24.

Therefore, according to the direct melting furnace 20, it is possible to prevent the dome from being broken as in the prior art, thereby causing fluctuations in the furnace temperature and the furnace pressure due to the dome. A stable waste gasification and melting process can be performed. At this time,
Since the straight body portion 22 is formed of a metal material having good heat conductivity such as copper and the inside is cooled by cooling water supplied from a cooling water pipe, the straight body portion 22 is formed in the combustion / melt region 23. The molten solid solidifies on the surface of the metal material and functions as a heat insulating layer, so that the surface of the straight body portion 22 can be protected. For this reason, the durability can be remarkably improved as compared with the conventional case where the side wall is made of a refractory. As a result, the continuous operation time in the direct melting furnace 20 can be greatly extended, and the operation cost can be reduced.

Further, since the injection nozzle 25 for the oxygen-enriched gas or the preheated air is mounted so as to be jetted toward the center of the furnace bottom 26 so as not to face the side wall, the flame jetted from the injection nozzle 25 causes the flame. Also, it is possible to prevent the side wall from being melted.

FIGS. 2 and 3 show the shapes of the inner walls of a modification of the embodiment shown in FIG. 1, respectively. The same components as those shown in FIG. Is omitted. In the direct melting furnace 35 shown in FIG. 2, a shelf 36 between the lower part of the pyrolysis zone 21 and the combustion / melt region 23 formed by the straight body 22 is constituted by an inclined surface 37 and a horizontal surface 38. Things. Further, in the direct melting furnace 40 shown in FIG. 3, a shelf 41 between the lower part of the pyrolysis zone 21 and the straight body 22 is constituted by a vertical surface 42 and an inclined surface 43 continuous with the pyrolysis zone 21. It was done. Even in the direct melting furnaces 35 and 40 shown in these modified examples, the same operation and effects as those shown in FIG. 1 can be obtained.

Next, FIGS. 4 to 6 show the inner wall shape in another embodiment of the present invention.
The same reference numerals are given to the same components as those shown in FIG. The direct melting furnaces 50, 51, 5 shown in FIGS.
2 is a direct melting furnace 2 having the shape shown in FIGS.
At 0, 35, and 40, the side wall 53 of the portion where the pyrolysis zone 21 is formed is formed in an inclined surface shape whose cross-sectional area gradually increases from above to below. As a result, in the direct melting furnace 52 shown in FIG. 6, one of the side walls 42 constituting the shelf 41 is formed in an inclined surface continuous with the side wall 53. These direct melting furnaces 50, 5
According to 1, 52, the same operation and effect as those shown in FIGS. 1 to 3 can be obtained, and further, the side wall 53 can promote the downward movement of the waste from the drying zone, Therefore, an effect is obtained that the waste can be moved more smoothly.

In the above embodiment, only the case where the direct melting furnaces 20, 35, 40, 50 to 52 are cylindrical is described, but the present invention is not limited to this. The same can be applied to a square direct melting furnace. In this case, the cross-sectional area of the square cylindrical straight body constituting the bottom is 1/10 to 7 times the cross-sectional area in the pyrolysis zone. It is more preferable to set a range of / 10.

[0024]

As described above, according to the direct melting furnace according to the present invention as set forth in any one of claims 1 to 5, the shelf provided at the lower part of the pyrolysis zone is stably used as a leg. A strong dome can be formed, thereby avoiding a sudden drop of waste and resulting fluctuations in furnace temperature and furnace pressure, and ensuring stable waste gas for a long period of time. A chemical fusing treatment can be performed. In particular, according to the second aspect of the present invention, since a portion whose sectional area is clearly narrowed is formed between the straight body portion and the shelf portion, the portion is more stable and can be used as a leg portion. According to the third aspect of the present invention, a strong dome can be formed.
Since the inclined surface near the connecting portion with the combustion / melting zone becomes more horizontal, the effect of forming the dome is improved.

Further, according to the invention described in claim 4,
The downward movement of waste from the drying zone is not hindered by the side walls where the pyrolysis zone is formed,
According to the fifth aspect of the present invention, it is possible to promote the smooth movement of the waste, and the molten solid generated by the high-temperature heat in the combustion / melting zone is solidified on the surface of the metal material. In order to function as a heat insulating layer, the surface of the metal material can be protected, so that the durability can be remarkably improved as compared with the conventional case where the side wall is made of a refractory. can get.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing an inner wall shape in a modification of the embodiment shown in FIG.

FIG. 3 is a longitudinal sectional view showing an inner wall shape of another modification of the embodiment shown in FIG. 1;

FIG. 4 is a longitudinal sectional view showing an inner wall shape according to another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing an inner wall shape in a modification of the embodiment shown in FIG. 4;

FIG. 6 is a longitudinal sectional view showing an inner wall shape of another modification of the embodiment shown in FIG. 4;

FIG. 7 is a longitudinal sectional view showing a conventional vertical shaft furnace.

[Explanation of symbols]

 2 Input port 6 Drying zone 20, 35, 40, 50, 51, 52 Direct melting furnace 21 Thermal decomposition zone 22 Straight body part 23 Combustion / melting zone 24 Slag outlet 25 Input nozzle (oxygen-containing gas inlet pipe) 26 Furnace Bottom 30 Dome 27, 36, 41 Shelf

Claims (5)

[Claims] 1. A waste inlet is provided at an upper or side body part, and an oxygen-containing gas introduction pipe is connected to a bottom part, so that drying and heating are sequentially performed inside from the inlet downward. A vertical shaft furnace in which each zone of decomposition and combustion / melting is formed, and a bottom portion where the combustion / melting zone is formed has a cross-sectional area smaller than that of the upper pyrolysis zone. As well as being formed
A direct melting furnace, wherein a shelf having a larger inclination angle with respect to a vertical line than the bottom is formed between the bottom and a lower portion of the pyrolysis zone. 2. The bottom part is a straight body part, and the sectional area of the bottom part is 1/1 of the sectional area in the pyrolysis zone.
2. The direct melting furnace according to claim 1, wherein the range is from 0 to 7/10. 3. The shelf according to claim 1, wherein the shelf is formed by a plurality of inclined surfaces whose inclination angle with respect to the vertical line increases gradually from above to below.
The direct melting furnace according to 1. 4. The method according to claim 1, wherein the portion in which the thermal decomposition zone is formed is formed such that its cross-sectional area gradually increases from above to below. Direct melting furnace. 5. The direct melting furnace according to claim 1, wherein the bottom side wall is formed of a metal material into which a cooling medium is introduced.