JPS6120766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to prevent smelt explosions in a flue gas conduit for guiding flue gas generated when waste liquid containing smelt explosive inorganic salts is incinerated to the next processing device while cooling it. Regarding equipment.

In the present invention, "smelt explosion" generally refers to "molten salt-water explosion".
It refers to the explosive phenomenon that occurs when high-temperature molten salt comes into contact with water.

Generally speaking, as a means of making waste liquid containing organic matter non-polluting, an incineration treatment device is known that sprays this waste liquid into an incinerator maintained at a high temperature of 800 degrees Celsius or higher and burns the organic matter in the waste liquid. . but,
If this waste liquid contains inorganic salts, they will melt at the high temperature, some will become particulates and accompany the combustion exhaust gas, and the rest will travel along the furnace wall in the form of a film or droplets. It will flow down like this. Traditionally, when this inorganic salt is non-smelt explosive, such as sodium carbonate or sodium sulfate,
The combustion exhaust gas and flowing molten salt can be guided directly into water to cool the combustion exhaust gas and remove the molten salt by dissolving it in the water, so this series of treatments can be efficiently performed using a relatively simple device with a sealed structure. It was possible. However, if at least some of these inorganic salts are smelt-explosive, such as sodium chloride or potassium chloride, cooling and dissolving with water as described above is difficult due to the risk of smelt explosion. Therefore, it had the disadvantage that it could not be processed efficiently in a closed system.

In recent years, as a device to eliminate these drawbacks,
The combustion exhaust gas conduit, which has a fountain nozzle at the top that sprays water in a thin stream or film form, and has a constricted part directly below it, is connected to the incinerator outlet, and descends from the outlet. A waste liquid incineration treatment device has been provided in which combustion exhaust gas and molten salt are cooled by water spray or the ventilate effect in a narrow area and are guided to the next treatment device, such as a gas-liquid separation can (Japanese Patent Publication No. 14548/1983). ). This device works by immersing the entire mass of molten salt in water, which instantly solidifies from the outside, and a portion of the water is wrapped inside the molten salt and evaporates, breaking the hardened outer shell. However, if only a part of the outer surface of the molten salt mass is brought into contact with water intermittently, the amount of water trapped inside is small, and the water evaporates. This was done with the aim of preventing smelt explosions because the water vapor generated by this process escapes through the outer surface of the soft part that has not come into contact with water and has not yet solidified. Further, the ventilly effect in the narrow portion not only accelerates cooling but also has many advantages such as being excellent in collecting soot and dust in the combustion exhaust gas.

However, as a result of various experiments conducted on this device, the inventors of the present invention have confirmed that a smelt explosion may occur at the constricted portion of the flue gas pipe, leading to destruction of the device. In other words, among smelt explosive molten salts, those with poor fluidity or those with growth properties tend to form large lumps, so water spraying as described above cannot provide sufficient cooling. Even after such treatment, if it comes into contact with a large amount of water, there is a risk of a smelt explosion leading to the destruction of the equipment, and if there is a malfunction such as a blockage of the fountain nozzle, there is a risk of insufficiently cooled molten salt being generated. . On the other hand, when incinerating waste liquid that generates molten salt, the amount of cooling water needs to be at least 1.5 times the amount of water that evaporates when cooling the combustion exhaust gas. This large amount of water flows down the combustion exhaust gas pipe, but at the constriction part whose diameter is gradually reduced toward the narrow part, it gradually collects into a stream in the narrow inner diameter part, and especially at the constriction part. A thick layer of water flows on the inner surface of the lower part of the tank. Therefore, when a lump of insufficiently cooled molten salt as mentioned above falls into this thick layer of water, a smelt explosion that can lead to equipment destruction is likely to occur.

The purpose of the present invention is to prevent smelt explosions that can lead to device destruction that occur at the constricted part of a combustion exhaust gas conduit that is provided with a fountain nozzle above and has a narrow part directly below it. of,
A smelt explosion prevention device covered with a perforated plate placed at an angle of 45° to 70° at an appropriate distance from the surface prevents some of the large amount of water flowing down to the constriction area.
The water flows to the back side of the perforated plate through the holes in the perforated plate that covers the inner surface of the constriction part, and maintains a thin layer of water on the perforated plate surface. The large chunks of molten salt that fall into the area are caught by the surface of the perforated plate, which is maintained in a thin layer of water, and are allowed to roll down on the perforated plate, thereby preventing the equipment from being destroyed at the constriction area. This is designed to prevent the occurrence of strong smelt explosions that could lead to smelt explosions.

This was made based on the following findings obtained through research by the present inventors. In other words, if a lump of molten salt is around 3g, it can be instantly cooled down to the center, so no matter what conditions it comes into contact with water, it will hardly explode as a smelt, and even if it does, it will be weak. , there is no possibility that the equipment will be destroyed. In addition, in the case of a lump of molten salt of about 5 g or more, even if only a part of the outer surface is brought into contact with water, if the contact surface is constant, it is extremely likely to cause a smelt explosion, A smelt explosion can also occur when a block of salt is dropped. This is thought to be because when the water is in a stationary state, water is trapped between the solidifying molten salt and the bottom of the water reservoir, and the water evaporates and expands, causing a smelt explosion phenomenon. This tendency is particularly noticeable in the case of molten salts that have poor fluidity and form large growing lumps. However, when water flows on a slope of 5° or more,
When molten salt rolls down this slope together with water, the contact surface between the water and the molten salt mass changes constantly, resulting in relatively slow solidification, and the solidifying molten salt Since no water is trapped between the bottom and the bottom of the stream, smelt explosions hardly occur even when the water depth is about 5 mm.

Generally, the constricted portion of the combustion exhaust gas conduit as described above has an inclined surface of 45° to 70° so as to obtain a sufficient ventilly effect in the narrowed portion. Therefore, it can be seen that smelt explosion can be prevented if the depth of water flowing on the inner surface of the constriction part is 5 mm or less. Furthermore, since the area near the constriction part is close to the incinerator and is easily exposed to high temperatures, it is relatively strong, so even if a smelt explosion occurs, it is unlikely to be damaged. The intensity of the explosion varies depending on the depth of the water into which the molten salt falls, but the larger the lump, the more violent the explosion will be, and considering the strength of the area near the constriction, even a lump of molten salt weighing up to about 20g will explode. In other words, an explosion will not destroy the device at all.

The present invention was made based on such knowledge, and in the present invention, first, the constriction part is covered with a perforated plate,
By allowing some of the falling water to flow to the back side of the perforated plate through the holes, the water depth on the surface of the plate can be kept shallow. On the other hand, large chunks of molten salt have difficulty passing through the holes in the perforated plate, so they roll down the surface of the perforated plate, come into contact with shallow water flowing on the perforated plate surface, and are cooled without causing a strong smelt explosion. It will become.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below based on the drawings.

FIG. 1 is a sectional view showing an embodiment of a waste liquid incineration treatment apparatus in which an incinerator and a gas-liquid separation can are connected by a flue gas conduit equipped with a smelt explosion prevention device according to the present invention. 1 in the diagram is the incinerator, and incinerator 1
The exhaust port 2 is a combustion gas conduit 4 having a narrow portion 3.
It is connected to the gas-liquid separation can 5 via the gas-liquid separation can 5, and has a substantially sealed structure. A fountain nozzle 6 is provided above and around the combustion exhaust gas conduit 4 to spray water or spray water in a thin stream or film. A constriction part 7 is formed between the upper part of the combustion exhaust gas conduit 4 and the narrow part 3, and the constricted part 7 gradually becomes thinner toward the narrow part 3. It's covered. Moreover, a fuel burner 9 and a waste liquid injection nozzle 10 are provided above the incinerator.

This incinerator 1 is maintained at a temperature (usually 800° C. or higher) sufficient to burn the organic matter in the waste liquid by combustion of fuel injected from a fuel burner 9. Therefore, when a waste liquid containing organic matter and inorganic salts is sprayed from the waste liquid injection nozzle 10 into the incinerator 1, the water in the sprayed waste liquid evaporates while descending in the incinerator 1, and the organic substances are completely burned. The inorganic salts on the other hand are melted. A part of the molten salt becomes particulate and accompanies the combustion exhaust gas, and the rest flows down along the inner wall surface of the incinerator 1 and reaches the discharge port 2. The combustion exhaust gas and molten salt flowing down from the exhaust port 2 are cooled by water injected from the fountain nozzle 6.

At this time, the supplied water is in the form of mist as described above.
Because it is in the form of a thin water stream, thin film, and high speed, it comes into contact with the molten salt partially or in some cases intermittently.
Since it is not completely covered with a water film, the molten salt can be cooled without causing a smelt explosion. However, if the molten salt is a large lump or the fountain nozzle 6 is blocked, molten salt that has not been sufficiently cooled will be formed on the inner surface of the constriction part 7 by the large amount of water sprayed from the fountain nozzle 6. There is a risk of explosion if the product falls into a thick film of water. Therefore, the inner surface of the constriction section 7 is covered with a perforated plate 8 disposed at an appropriate distance from the said surface, and a portion of the water and small molten salt is passed through the holes of the perforated plate 8 to its back surface. It flows to the side and flows down along the inner surface of the constriction part 7, and the large lumps of molten salt roll down on this perforated plate 7 and flow into the narrow part 3 without coming into contact with a large amount of water.
It is now possible to lead to

When the exhaust gas reaches the narrow portion 3 in this way, the soot and dust in the exhaust gas is collected by water and flows through the combustion exhaust gas conduit 4 to reach the gas-liquid separation can 5.

The gas-liquid separation can 5 has an oblong cylindrical shape, and the combustion exhaust gas conduit 4 is connected to one side thereof.
Directly below the combustion exhaust gas conduit 4 in the gas-liquid separation can 5, a perforated plate 11 is installed at an angle θ of about 5° to 60° (see Figure 2), and a manhole is connected from near the lower end of this perforated plate 11. A further perforated plate 13 extends parallel to the bottom up to the other side on which the plate 12 is provided.

Water and small molten salts falling from the combustion exhaust gas pipe 4 fall downward while flowing on the perforated plate 11, and the molten salts are dissolved in the water and flow out from the drain port 14. In addition, the large lumps of molten salt roll from the perforated plate 11 to the perforated plate 12, and the incinerator 1 discharge port 2
It is cooled and dissolved by water sprayed from a fountain nozzle 15 similar to those provided around the area. On the other hand, the combustion exhaust gas is discharged from the exhaust port 16 after the soot dust that cannot be completely collected by the combustion exhaust gas conduit 4 is removed by water injected from the fountain nozzle 15 .

FIG. 2 is an enlarged longitudinal cross-sectional view of the vicinity of the throttle part of the combustion exhaust gas conduit, and FIG. 3 is a cross-sectional view. As shown in the figure, the perforated plate 8 is installed parallel to the constriction part 7. However, the perforated plate 8 does not necessarily have to be parallel to the constricted part 7, and if an appropriate distance can be obtained from the inner surface of the constricted part 7 and there is no gap where a large lump of molten salt can enter, the perforated plate 8 should be oriented at an angle. θ to 45°
Can be arbitrarily selected within the range of 70°. If it is less than 45 degrees, it will be difficult to obtain the ventilate effect in the narrow part 3, and if it exceeds 70 degrees, the combustion exhaust gas pipe 4 will be elongated, which is extremely disadvantageous from a structural standpoint.

The size of the hole is preferably about 8 mm to 30 mm in diameter. If the perforated plate is too small, it will easily become clogged, and if it is too large, large chunks of molten salt will be removed from the perforated plate 8.
This will cause it to flow to the back side. Furthermore, as the angle θ of the porous plate 8 increases, the amount of water and a portion of small molten salt flowing through the holes to the back side of the porous plate 8 decreases, so that the holes can be made larger.
The porosity is preferably set as uniformly as possible within the range of 20% to 50%, in view of preventing uneven water depth on the perforated plate and its strength.

If the inner surface of the constriction part 7 is covered with the perforated plate 8 in this way, a part of the water and small molten salts jetted from the fountain nozzle 6 will flow from the holes of the perforated plate 8 to the back side of the perforated plate 8 and be restricted. As a result, a large lump of molten salt rolls down on the perforated plate 7, which has a small amount of water, and there is no fear that a smelt explosion will occur in the constriction part 7, which could lead to equipment destruction. .

As explained above, according to the present invention, it is possible to prevent smelt explosions that would lead to equipment destruction, and increase the soot dust collection effect by the ventilate effect, making it an extremely effective incineration process for waste liquid incineration. This has the advantage that not only a device can be obtained, but also a conventional device can be easily improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a waste liquid incineration treatment device in which an incinerator and a gas-liquid separation can are connected by a combustion exhaust gas pipe equipped with a smelt explosion prevention device according to the present invention, and FIG. FIG. 3 is an enlarged longitudinal cross-sectional view of the vicinity of the constriction part of the exhaust gas conduit, and FIG. 3 is an enlarged cross-sectional view of the vicinity of the constriction part of the combustion exhaust gas conduit. 1: Incinerator, 2: Discharge port, 3: Narrow part, 4: Combustion exhaust gas pipe, 5: Gas-liquid separation can, 6: Fountain nozzle, 7: Throttle part, 8: Perforated plate, 9: Fuel burner, 10: Waste liquid injection nozzle, 11: Perforated plate, 1
2: Manhole, 13: Perforated plate, 14: Drain port,
15: Fountain nozzle, 16: Exhaust port.

Claims (1)

[Claims] 1. In order to cool and guide the combustion exhaust gas containing smelt explosive molten salt, a fountain nozzle is provided above which sprays water or sprays water in a thin stream or film form,
In a combustion exhaust gas conduit that has a narrow part directly below it, the inner surface of the constricted part that gradually narrows from the top toward the narrow part is placed at an appropriate distance from the said surface.
A smelt explosion prevention device characterized by being covered with perforated plates arranged at an angle of 70 degrees. 2. The smelt explosion prevention device according to claim 1, wherein the holes in the perforated plate have a diameter of 8 mm to 30 mm.