JPH01288387A - Melting furnace for industrial waste - Google Patents

Abstract

PURPOSE:To extend the life of a melting furnace by constituting the furnace wall of the melting furnace of refractory containing a fine molten slag powder of a material to be melted. CONSTITUTION:Coke oven gas is blown in a melting furnace from a stabilizing burner 10 along with combustion air preheated to predetermined temp. to be burnt and the furnace wall 17 of said furnace 2 is held to temp. so as to become higher by 50-100 deg.C than the melting temp. of ash. Subsequently, ash is transported by a predetermined amount by an ash supply device 3 in this state so as to be carried by an air stream. The ash is uniformly mixed with combustion air in an ejector 13 and a solid-air two-phase steam wherein combustion air is mixed with the ash is formed into a strong revolving stream by the revolving blade of the burner 10 to be uniformly injected in a combustion chamber A. The ash is burnt rapidly while collides with the furnace wall 17 by centrifugal force to fall in a molten slag pot 9a and received in a cooling and solidifying device 15 from a cinder notch 9b. By this method, the life of the furnace wall can be extended to a large extent.

Description

[Detailed description of the invention] [Industrial application field] The present invention uses coal ash produced by incinerating coal and municipal waste.

Industrial waste such as sewage sludge, general waste, etc.

The present invention also relates to a melting furnace for melting incineration ash obtained by incinerating the industrial waste, and particularly relates to a structure capable of extending the life of the furnace wall of the melting furnace.

[Conventional technology]

When disposing of industrial waste such as municipal garbage, sewage sludge, and general waste, the industrial waste is either directly buried in a landfill, or the industrial waste is incinerated to form incineration ash and then buried in a landfill. Furthermore, most of the coal ash discharged from boilers, kilns, industrial furnaces, etc. that use coal as fuel is disposed of in landfills.

However, in recent years, as the amount of industrial waste mentioned above has been increasing year by year, it has become difficult to secure land for landfill, and secondary pollution is occurring due to the outflow of hazardous substances from these landfilled wastes. This is a concern, making landfill disposal difficult.

Therefore, attention has been paid to a melt processing method in which the above-mentioned incineration ash 1 coal ash (hereinafter referred to as ash) and industrial waste such as sewage sludge sludge are melted into slag and then cooled and solidified. By this melting treatment, the volume of the industrial waste to be disposed of can be reduced, harmful substances can be immobilized, it can be used for landfill, and the molten slag can be effectively used for civil engineering, building materials, etc.

When melting the industrial waste mentioned above, most of the time, high-temperature melting using heat sources such as coke, electricity, various fuels, and microwaves is used, and a melting furnace that maintains the material to be melted at a high temperature is essential. .

In this melting furnace, it is necessary to maintain the inside of the furnace at a high temperature and minimize heat loss, so a refractory is installed inside the iron plate that makes up the furnace shell.

By the way, in the above-mentioned melting furnace, since various substances are contained in the material to be melted, there is a problem that these substances tend to react with the above-mentioned refractory and corrode it under high-temperature conditions. As a result, it is often necessary to stop the operation of the melting furnace to repair the furnace wall, or to switch to operation with a spare melting furnace, which increases repair costs and equipment costs. Therefore, extending the life of the refractories is a very important issue.

Conventionally, a refractory with a relatively long life has been selected from various commercially available refractories for the walls of the melting furnace.

[Problem that the invention seeks to solve]

However, with the conventional method of selecting the optimal refractory from among the refractories described above, it is difficult to sufficiently suppress the erosion rate, and there is a problem that the life of the furnace wall cannot be extended much.

Here, in order to extend the life of the above-mentioned refractories, the inventor conducted a melting test of each object to be melted using various refractories that are generally commercially available. It was also concluded that it is very difficult to control erosion. This is because the composition of municipal waste, sewage sludge, etc. differs depending on where it is generated, and even if municipal waste is brought to the same treatment plant, the composition may vary depending on the date of treatment. Therefore, it is difficult to select refractories.

The present invention was made in view of the above-mentioned conventional situation, and even if the composition of the material to be melted changes, it is possible to suppress the erosion rate of the refractory, extend the life of the furnace wall, and reduce repair costs and equipment costs. The purpose is to provide melting furnaces for industrial waste.

[Means for solving problems]

As a result of extensive studies in order to extend the life of the refractory, the inventor of the present invention found that rather than finely adjusting the various components of the refractory material in order to respond to the fluctuations in each component of the refractory material, We thought it would be desirable to use a refractory that is insensitive to changes in composition. Based on the idea that materials to be melted are unlikely to react with each other, if the inner wall of the melting furnace is protected by the materials to be melted, it will be possible to minimize the possibility of reactions occurring, and to obtain a refractory that is insensitive to changes in composition. The present invention was developed based on the idea that this would be the best in terms of technology and cost compared to the case of using a refractory material in which the various components of the refractory material are finely adjusted.

Therefore, the present invention is characterized in that the inner wall of the industrial waste melting furnace is made of a refractory material containing at least 50% or more by weight of pulverized molten slag of the material to be melted or ash of the material to be melted.

Here, the material to be melted includes municipal garbage, sewage sludge, general waste, incineration ash obtained by incinerating these, or coal ash obtained by incinerating coal.

Further, the reason why the above content is set to 50% or more is because if it is less than this, the effect of suppressing the erosion rate cannot be obtained much. This was determined based on the need to suppress the erosion rate to 51 or less per month in order to reduce the frequency of repair of refractories. Furthermore, as the content increases beyond 50%, the erosion rate decreases, but when the content is increased to 100%, the binder effect decreases and the strength of the refractory decreases, and the melting temperature of the furnace wall decreases. Caution is required.

Taking these things into consideration, it is desirable to set it in the range of 60 to 90%.

[Function] According to the industrial waste melting furnace according to the present invention, the molten slag powder of the object to be melted is added to the refractory constituting the furnace wall of the melting furnace.
Alternatively, since the ash content is 50% or more, melted materials of approximately the same composition come into contact with each other during high-temperature melting, and in other words, they protect themselves against substances that corrode refractories, so corrosion due to reactions is prevented. can be significantly suppressed, and even if a change in the composition of the material to be melted occurs, the reaction becomes insensitive, and from this point of view as well, erosion can be suppressed. As a result, the life of the furnace wall can be significantly extended, the frequency of repairs can be reduced, and operating costs and equipment costs can be reduced.

In addition, since the present invention only requires mixing the above-mentioned molten slag powder etc. with commercially available refractories, it is technically less expensive than the case where various components of the refractory material are finely adjusted according to each component of the refractory material to be melted. It is advantageous in terms of cost.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 are diagrams for explaining one embodiment of the present invention, and this embodiment is an example of a furnace for melting incinerated ash and coal ash.

In the figure, ■ is an incineration ash 6 coal ash melting processing device. This processing device 1 includes a vertical melting furnace 2, a supply device 3 that pneumatically transports ash stored in a storage bottle 3a to the melting furnace 2 using compressed air 3b, and a supply device 3 that supplies combustion air to the melting furnace 2. a combustion air supply device 4 for recovering the waste heat of the exhaust gas from the melting furnace 2, a heat exchanger 5 for preheating the combustion air, and capturing untreated ash in the low temperature exhaust gas from the heat exchanger 5. It is composed of a dust collector 6 that collects dust.

The melting furnace 2 has a fuel inflow part 8 connected by a flange to the upper end of a cylindrical furnace body 7 in which a combustion chamber A is formed, a slag storage part 9 to the lower end, and a lower part of the furnace body 7. An exhaust gas outflow portion 7a is formed in the exhaust gas outflow portion 7a.

A burner tile 8a is formed in the fuel inlet 8, and an auxiliary burner 10 is attached to this.

A solid-gas two-phase flow supply pipe 11 and a fuel supply pipe 12a are connected to this auxiliary combustion burner 10.
The extended end of the coke oven gas supply device 12 is connected to the coke oven gas supply device 12 . Further, a T-tube type ejector 13 is connected to the solid-gas two-phase flow supply pipe 11, and the ejector 13 is connected to the ash supply pipe 3c of the ash supply device 3 and the heat exchanger 5.
Combustion air supply pipe 4 that supplies combustion air preheated by
b is connected, and the extended end of this combustion air supply pipe 4b passes through the heat exchanger 5 and is connected to the blower 4a. The ejector 13 is configured to mix air-transported ash into combustion air in advance and supply it to the burner 10 as a solid-gas two-phase flow. The fuel is injected into the combustion chamber A by being given a swirl by swirling vanes arranged in the combustion chamber A.

Furthermore, the exhaust gas introduction section 5a of the heat exchanger 5 is connected to the exhaust gas outflow section 7a, and the dust collector 6 is connected to the discharge section 5b thereof. Further, this dust collector 6 is connected to a chimney 14 via an induction fan 6a.

Further, a slag bot 9a serving as a slag storage section is located below the combustion chamber A, and a slag outlet 9b is formed protruding from this slag bot 9a. As a result, the molten slag collected in the bowl 9a is extracted from the slag outlet 9b and collected in the cooling assimilation device 15.

The furnace body 7 of the melting furnace 2 has an iron shell 7b constituting the furnace shell.
A cooling water jacket 16 is formed on the outermost periphery of the cooling water jacket 16, and a cooling water inlet 16a is formed in the lower part of the jacket 16, and an outlet port 16b is formed in the upper part of the jacket 16. and,
A furnace wall 17 having a thickness of 100 mm in the radial direction is formed on the inner circumferential surface of the iron shell 7b of the furnace body 7. This furnace wall 17
The refractory is lined with a refractory made of mixed powder of alumina cement mixed with 50% or more by weight of fine molten slag powder. Note that the cooling water jacket 16 is not necessarily necessary, and the furnace wall 17 may be thickened to have a non-water-cooled structure, or a self-cooling structure may be provided.

Next, the effects of this embodiment will be explained.

When ash is melted and solidified by the melting processing apparatus 1 of this embodiment, coke oven gas and combustion air preheated to a predetermined temperature are blown into the melting furnace 2 from the auxiliary combustion burner IO and burned, so that the furnace wall 17 becomes the ash. The melting temperature is maintained at 50 to 100°C higher than the melting temperature.

For example, coal ash is kept at 1550°C, and sewage sludge incineration ash is kept at 1400°C. Next, in this state, the ash supplying device 3 transports the ash in a predetermined amount at a time. Then, the ash is uniformly mixed into the combustion air in the ejector 13,
This solid-gas two-phase flow in which combustion air and ash are mixed is uniformly injected into the combustion chamber A by being given a strong swirling flow by the swirling vanes of the burner IO. As a result, the ash forms a spiral and rapidly burns while colliding with the furnace wall 17 due to centrifugal force, and then turns into molten slag and falls into the slag pot 9a, and is passed through the slag outlet 9b into the cooling assimilation device. 1
It is accommodated in 5. On the other hand, the exhaust gas enters the heat exchanger 5 through the outflow passage 7a, where waste heat is recovered, and untreated ash in the exhaust gas is collected and purified by the dust collector 6, and then the chimney 14 released from.

Ash that has been melted and solidified in this way can be used in landfills because it can reduce the volume of disposal volume and immobilize harmful substances, and it can also be used in civil engineering, l! Can be used as construction material.

When the ash is melted, the ash contains various substances, and in conventional equipment, these substances tend to react with the furnace wall and erode it, and the components in the ash are easily eroded. The problem is that it erodes quickly and has a short lifespan because it fluctuates depending on various conditions. On the contrary,
In this example, the furnace wall 17 of the melting furnace 2 is made of a refractory material in which 50% or more by weight of fine molten slag powder is mixed with a generally commercially available mixed powder of alumina cement, thereby promoting cell coating. Therefore, reactions during high-temperature melting can be prevented, the erosion rate can be reduced, and the life of the furnace wall can be significantly extended. As a result, the amount of repairs can be reduced, and thus operating costs and equipment costs can be reduced.

In addition, according to this embodiment, it is only necessary to mix molten slag powder with commercially available alumina cement powder. It is technically easier and the manufacturing cost can be reduced compared to the conventional method.

In the above embodiments, the case where molten slag powder was mixed with the refractory was explained as an example, but this is because the properties of the slag itself are stable.

However, the present invention is not limited to this slag powder, and ash that does not contain flammable substances may be mixed.
Even in this case, the same effects as in the above embodiment can be obtained.

In addition, it is better to use the molten slag powder in a one-to-one relationship, such as when the object to be melted is municipal garbage, the molten slag of the municipal garbage, and when the object is sewage sludge, the molten slag of the sewage sludge. It is more effective in achieving this goal.

Furthermore, in the above embodiments, the explanation was given using a swirling flow type melting furnace as an example, but the melting furnace of the present invention is of course not limited to this, and in short, any furnace wall of an industrial waste melting furnace can be used. can also be applied.

FIG. 3 is a characteristic diagram showing the relationship between the erosion rate of the furnace wall and the mixing ratio of molten slag powder to explain the results of an experiment conducted to confirm the effects of this example.

In this experiment, the furnace wall 17 was constructed of a refractory material in which 20 to 100% by weight of molten slag powder was mixed with alumina cement mixed powder in the melting processing apparatus 1 of this embodiment. 250 kg/h of coal ash and sewage sludge ash
The erosion rate of the furnace wall 17 when it was supplied and burned and melted was investigated. In addition, in this experiment, a conventional refractory made only of alumina cement mixed powder was also used for comparison.
The mark indicates coal ash, and the mark indicates sewage sludge ash.

As is clear from Figure 3, with conventional refractories, 0.11 layers of coal ash and approximately 3 layers of sewage sludge ash per hour.
However, in the refractory of this example,
As the molten slag powder increases, the erosion rate increases
It can be seen that both have decreased significantly. In addition, the furnace wall 17
In order to suppress the erosion rate to less than 5 yen per month, it is necessary to set it to 0.007 m per hour, and to meet this requirement, it is sufficient to contain the molten slag powder in an amount of 50% or more. According to this experiment, it was found that when the slag powder was increased to 100%, the binder effect that binds the powders to each other decreased, making the refractory more brittle and lowering its strength. Therefore, the amount of molten slag powder added is preferably in the range of 60 to 90%.

〔Effect of the invention〕

As described above, according to the industrial waste melting furnace of the present invention, the furnace wall of the melting furnace is made of a refractory mixed with molten slag powder of the material to be melted or ash at a weight ratio of 50% or more. ,
It has the effect of suppressing the erosion rate and significantly extending the life of the furnace wall.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining a melting furnace for industrial waste according to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of the melting processing apparatus, and FIG. FIG. 3 is a characteristic diagram showing the relationship between the erosion rate of the furnace wall and the mixing ratio of molten slag powder. In the figure, 2 is a melting furnace, and 17 is a furnace wall. Patent Applicant Kobe Steel Co., Ltd. Representative Patent Attorney Tsutomu Shimoichi Figure 2 Car 7

Claims (1)

[Claims] (1) A melting furnace for melting industrial waste such as coal ash, municipal garbage, sewage sludge, etc., in which the furnace wall of the melting furnace is covered with molten slag powder of the material to be melted or A melting furnace for industrial waste, characterized in that it is constructed of a refractory material containing 50% or more of industrial waste ash by weight.