JPH03156287A - High temperature treating device for substance - Google Patents

Abstract

PURPOSE:To suppress damage of an inner wall in a processing chamber, and to reduce a repairing cost, a facility cost by forming a refractory material of the inner wall of a part in direct contact with high temperature substance or atmosphere of a refractory metal member, and forming composition of the member of simple chromium or specific chromium alloy. CONSTITUTION:Refractory wall member 18 of the wall 17 of a melting furnace 2 and the inner wall 9c of a slag container of an incinerating ash, coal ash melting processor 1 are formed of refractory bricks 19 and a refractory alloy plate 20 adhered to the surface of the brick. The composition of the plate 20 is formed of simple chromium or chromium alloy containing one or more types of W, Mo, Nb, Ta, V of 30% or less of weight ratio in the chromium. The brick 19 is adhered to the plate 20 by forming an adhering rib 20a on the rear surface of the plate 20. Since the wall 17 is formed of the bricks 19 covered with the plate 20, the brick 29 is not brought into direct contact with the slag, the plate 20 self-generates a film to be scarcely peeled or dispersed. Even if it is cracked, it is self-recovered. Accordingly, the plate 20 is not brought into direct contact with the slag.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an incinerator for incinerating industrial waste such as municipal garbage, sewage sludge, and general waste, and for melting and processing the incinerated ash of these wastes. Melting furnaces, as well as blast furnaces and converters in steel plants,
The present invention relates to high-temperature processing equipment for materials such as various hot metal processing furnaces, and particularly to improvements in the corrosion resistance and erosion resistance of furnace wall members.

[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, the above-mentioned incinerated ash 0 coal ash (hereinafter referred to as ash) is used.

), and a melt processing method in which industrial waste such as sewage sludge is turned into molten slag and then cooled and solidified is attracting attention. By this melting treatment, the amount of industrial waste to be disposed of can be reduced, harmful substances can be fixed, and the molten slag can be used for landfilling, and the molten slag can be effectively used for civil engineering, building materials, etc.

Most of the above industrial wastes are melted using high-temperature melting using heat sources such as coke, gas, various fuels, and microwaves, and a melting furnace that maintains this molten material at a high temperature is essential. . This melting furnace requires keeping the inside of the furnace at a high temperature and minimizing heat loss.
Refractories are installed inside the steel plates that make 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.

For this reason, in the past, refractories with a relatively long life were selected from various commercially available refractories for the walls of the melting furnace. Magnesia Chromia (M g O Cr z
Os) type refractories, etc.

[Problem that the invention seeks to solve]

However, as described above, with the conventional method of selecting the optimum refractory from among refractories, 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 refractory, the inventor conducted a melting test of each object to be melted using various commercially available refractories. We concluded that it is extremely difficult to suppress erosion even in materials.

There are two reasons for this; one is municipal garbage.

The composition of sewage sludge differs depending on where it is generated, and even when municipal waste is brought to the same treatment plant, its composition changes depending on the date of treatment, so refractories should be selected according to these conditions. The point is that it is difficult.

Another point is that the main constituents of both the refractory and the material to be melted, such as molten slag, are approximately the same type of oxide.

Specifically, the dissolution reaction of a solid into a liquid, such as the mechanism of erosion of refractories by molten slag, is dominated by either interfacial reaction rate-limiting or mass transfer through an interfacial reaction layer, that is, diffusion-limiting. It is thought that there are. Of these, the reaction between the refractory and the molten slag is said to be mainly due to the rate-limiting diffusion of the latter.

For example, a typical A I g O s 5ift-based refractory has a typical slag composition of C a O,S i
The mechanism of the reaction that causes corrosion and erosion by Ox/Alt Ox -MgO slag is that the ions of the refractory constituent elements and the slag constituent elements pass through the reaction layer that occurs between the refractory and the slag, that is, the boundary layer that forms at the interface between the two. It is said that interdiffusion of ions is the rate-determining step, and the concentration difference on both sides of the boundary layer is the driving force for the reaction. Therefore, the higher the solubility of the refractory constituent elements in the molten slag, the thinner the boundary layer thickness, and the higher the temperature, the higher the erosion rate.

If we look at the composition of blast furnace slag and sewage sludge slag, we find that both of them are Stow, AI! Os
+ Ca O + Consisting of a mixture whose basic composition is Fez Os, with small amounts of T I Ox , MnO, Mg
O+ P z Os + N a z O+ Kg
Contains O, S, v, and os, which have strong edible properties. Therefore, since both the refractory and the molten slag basically have substantially the same type of oxide as their main constituents, the higher the solubility of each constituent element in the molten slag, the faster the erosion becomes.

In addition, the boundary layer shown here is mostly a liquid phase with high viscosity locally near the solid surface, so when fresh slag is constantly flowing and in contact with it, such as in a blast furnace slag gutter, Or, if the slag itself is constantly agitated, the formation of a boundary layer cannot be expected, so even magnesia/chromia <Mg0-Cr, 02) will continue to erode due to the corrosion/erosion mechanism described above. I will do it. As a result, existing refractories have extremely short lifetimes.

The present invention was made to solve these problems, and aims to suppress damage to the inner wall of the processing chamber due to contact with highly corrosive and erosive slag in a high-temperature combustion gas atmosphere. The object of the present invention is to provide a high-temperature treatment device for materials that can reduce repair costs, equipment costs, etc.

[Means for solving problems]

A high-temperature processing apparatus for substances according to the present invention is a high-temperature processing apparatus for substances in which a substance is incinerated or melted in a processing chamber whose inner wall is made of a refractory material, wherein at least the high-temperature substance or high-temperature atmosphere on the inner wall of the processing chamber is The refractories in direct contact are made of refractory metal members, and the composition of the refractory metal members is chromium alone or chromium containing W, Mo, Nb, Ta.
, V at a content of 30% or less by weight.

The reason for employing the structural acid F in the present invention will be explained in detail below.

The inventor of the present invention discovered that in order for the refractory member used for the furnace wall of a melting furnace to have high corrosion resistance and erosion resistance in the above-mentioned high-temperature combustion gas atmosphere, it is necessary to make sure that the refractory member used for the wall of a melting furnace, etc., has high corrosion resistance and erosion resistance during the operation of the melting furnace, etc. We thought it would be desirable to self-generate a film that is resistant to IJ separation and dispersion at high temperatures to avoid direct contact with molten slag, and to also have the ability to self-repair even if cracks occur in the film. . We focused on metal materials as having these functions, and as a result of researching the reactivity of various metal materials with various slags, we developed a new refractory metal component that does not exist in the heat-resistant components currently in practical use. We have discovered that chromium and chromium-based alloys are extremely effective. As a result of experiments in actual plants, chromium alloys have a lifespan more than 100 times longer than magnesia/chromia refractories, which are considered to have the longest lifespan among existing refractories, and are a revolutionary alternative to conventional refractories. It was demonstrated that it is a highly functional metallic material.

In addition, in order to extend the life of this refractory metal component, it is desirable that the above-mentioned film forms gradually and always adheres to the base material in a thin layer, and from this point of view, suppressing the diffusion of chromium atoms will extend the life. discovered that it satisfies the requirements of Furthermore, if one of W Mo, Nb, Ta, or V, which is an element with a larger atomic radius than chromium and a higher heat resistance than chromium, is added alone or in combination with two or more of these metals, the effect will be even more effective. I also discovered that it is true. However, since these elements are easily oxidized and volatilized at high temperatures, adding large amounts will actually worsen the corrosion resistance and shorten the life of the material. Therefore, based on the results of the performance test described below, the upper limit of the amount added alone or in combination was set at 30 wt%.

As a result, the specific composition of the refractory metal member is W.

One or more of Mo, Nb, Ta, and V at θ~30
It can be a chromium alloy (first alloy composition) containing i+t% and the remainder consisting of chromium and unavoidable impurities.

Furthermore, in order to make the film formed on the refractory metal member having the first alloy composition even more adhesive, that is, less likely to peel off, Zr, Hf, and Y are added.

It has been found that one type of Ce and La may be added alone or two or more types may be added in combination.

The effect of this additional addition remains the same regardless of whether it is added alone or in combination, and based on the experimental results described later, the upper limit has been set to 5.
It was set as wt%.

As a result, the further composition of the refractory metal member is W.

O''-3 one or more of Mo, Nb, Ta, and V
Contains 0wt%, and further contains Zr, Hf, Y, and Ce.

A chromium alloy (second alloy composition) containing one or more kinds of La in an amount of 0 to 5 wt% and the remainder being chromium and unavoidable impurities can be used.

In addition, the heat-resistant alloy mentioned here may be one that has H that forms a self-generating and self-repairing oxide film during use at high temperatures, and even chromium itself has sufficient corrosion resistance. Experiments have demonstrated that it has corrosion resistance.

For this reason, the composition of the above-mentioned refractory metal member is the first. Chromium alone may be used instead of the second alloy composition.

As a result of the above-mentioned intensive research, the inventor of the present invention has discovered that if such metal materials are used to construct the furnace walls or to coat the exposed surfaces of refractory bricks inside the furnace, corrosion and erosion can be inhibited. The present invention was developed based on this idea.

[Effect]

In this invention, the refractory of at least a portion of the inner wall of the processing chamber that is in direct contact with a high-temperature substance or a high-temperature atmosphere is made of a refractory metal member, and the refractory metal member is made of chromium alone or the above-mentioned first. Since it is constructed from a chromium alloy with the second alloy composition, this refractory metal member self-generates a film that is difficult to peel off or break up in a high-temperature combustion gas atmosphere, and avoids direct contact with molten slag. If a crack occurs in the refractory metal member, it will self-repair, thereby protecting the refractory metal member itself. Further, by covering the surface of the refractory brick with a refractory metal member, the refractory brick is protected by the refractory metal member. As a result, corrosion and erosion of the walls of the processing chamber can be suppressed and its lifespan can be significantly improved.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 3 are diagrams for explaining a high-temperature processing device for substances according to an embodiment of the present invention, and here, an incineration ash 2 coal ash melting processing device is cited as an example of the processing device. There is.

In the figure, l is a melting processing bag for incinerated ash 5 coal ash! It is. 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 that collects waste heat from the exhaust gas from the melting furnace 2 and preheats the combustion air, and a heat exchanger 5 that collects untreated ash in the low-temperature exhaust gas from the heat exchanger 5. It is composed of a dust collector 6.

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 IO is attached to this.

A solid-gas two-phase flow supply pipe 1) and a fuel supply pipe 12a are connected to this auxiliary combustion burner 10.
The extended end of is connected to a fuel gas (coke oven gas) supply device 12 . A T-shaped ejector 13 is connected to the solid-gas two-phase flow supply pipe 1), and the ejector 13 is preheated by the ash supply pipe 3C1 of the ash supply device 3 and the heat exchanger 5. A combustion air supply pipe 4b is connected thereto, and an 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 swirling vanes (not shown) disposed 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. Also, this dust collection bag! 6 is connected to the chimney 14 via an induced fan 6a.

Further, a slag bot 9a of the slag accommodating portion 9 is located below the combustion chamber A, and a slag outlet 9b is formed protrudingly from this slag bot 9a. As a result, the molten slag collected in the bot 9a is extracted from the slag outlet 9b and collected in the cooling and solidifying device 15.

Further, the inner wall 9C of the slag accommodating portion 9 is composed of a fireproof wall member 18.

The furnace body 7 of the melting furnace 2 has an iron shell 7b constituting the furnace shell.
A cooling jacket 16 is formed on the outermost periphery of the cooling jacket 16, and a cooling water inlet 16a is formed in the lower part of the cooling jacket 16, and a cooling water outlet 16b is formed in the upper part. A fireproof wall member 1 is provided on the inner circumferential surface of the iron skin 7b of the furnace body 7.
The furnace wall 17 is constructed by lining the furnace wall 8. Note that the cooling water jacket 16 is not necessarily necessary;
The furnace wall 17 may be made thick so that it has a non-water-cooled structure, or it may have a self-cooling structure.

Further, here, this furnace wall 17 and the slag storage part inner wall 9
As shown in FIG. 3, the fireproof wall member 18 of C is composed of a refractory brick 19 and a refractory alloy plate 20 joined to the surface thereof.

Further, to join the refractory brick 19 and the refractory alloy plate 2o, a joining rib 20a having a trapezoidal cross section is formed on the back surface of the refractory alloy plate 20, and the refractory brick 19 is joined to the back surface of the refractory alloy plate 3. This is done by forming the lip 3a to be embedded within the brick 2.

The above refractory brick 19 is Aj! zOs, S i
Ox.

The refractory alloy plate 2o is made of a mixture of SiC, MgO, Cab, CrtC)+, etc., and the fireproof alloy plate 2o is made of W and Mo.

The first alloy composition contains 0 to 30% of one or more of Nb, Ta, and V, and the remainder is chromium and inevitable impurities.

Next, the effects will be explained.

In such a melting furnace, coke oven gas and combustion air preheated to a predetermined temperature are blown into the melting furnace 2 from the auxiliary burner 10 and combusted, so that the furnace wall 17 has a temperature higher than the melting temperature of ash by about 50 to 100°C. For example, 1550℃ for lime ash and 14℃ for sewage sludge incineration ash.
In this state, a predetermined amount of ash is air-transported by the ash supply device 3. Then, the ash is uniformly mixed into the combustion air in the ejector 13, and the ash is mixed with this combustion air. The mixed solid-gas two-phase flow is given a strong swirling flow by swirling vanes (not shown) of the burner 10 and is uniformly injected into the combustion chamber A. As a result, the ash forms a spiral and rapidly burns as it collides with the furnace wall 17 due to centrifugal force, and then turns into molten slag and falls into the slag pond 9a, where it is cooled and solidified from the slag outlet 9b! l
1ii! It is accommodated in 15. On the other hand, the exhaust gas flows through the outflow passage 7
The exhaust gas enters the heat exchanger 5 through the exhaust gas, where the waste heat is recovered, and then the untreated ash in the exhaust gas is collected by the dust collector 6, cleaned, and then released from the chimney 14.

When the ash is melted, the ash contains various substances, and in conventional equipment, these substances tend to react with the furnace walls and erode them, shortening the lifespan of those parts. There was a problem.

On the other hand, in this embodiment, the furnace wall 17 of the melting furnace 2 is
Fireproof wall member 18. In other words, since it is constructed of refractory brickwork 9 whose surface is covered with a refractory alloy plate 20, there is no direct contact between the refractory brick 19 and molten slag, and the refractory alloy plate 20 is placed in a high-temperature combustion gas atmosphere. It self-generates a film that is difficult to peel or break up, and even if a crack occurs in the film, it self-repairs. Therefore, the refractory alloy plate 20 also does not come into direct contact with the molten slag.

Therefore, damage caused to the furnace wall members due to corrosion or erosion can be greatly reduced, thereby greatly extending the life of the furnace wall. As a result, the frequency of repairs can be reduced, so operating costs and equipment costs can be reduced.

Next, the results of testing the corrosion resistance and erosion resistance of the above-mentioned chromium and chromium-based alloy using an actual plant will be explained using the attached table and the graph in FIG. 4.

The test consisted of test pieces of chromium-based alloys (sample floors 1 to 38) with the compositions shown in the table, and magnesia-chromia bricks (sample floors 1 to 38), which are said to have the best corrosion resistance of this type of refractory, as comparison materials. Sample No. 39) was used. The test method was to melt these test pieces in vacuum, and then use a heating furnace to conduct a immersion test on the test pieces cut out from the ingots in molten slag at a temperature of 1500°C for 200 hours. In addition, the corrosion resistance and erosion resistance were evaluated by measuring the amount of decrease in wall thickness (one side) of the test piece after the test.

The heating furnace used is a fluidized bed type heating furnace that continuously supplies synthetic slag in a molten state having the following composition range.

Slag composition; Sin, -IQ~40%, Altoz1)
=5~20% F ex Os -0~20%, CaO -10~40%
T i Oz =0.2~3%, pg os -3~2
5%MgO-1~7%, NagO=0.3~5%□
O-0,2~3% S -0,3~5%Vx Os
"0.2~3% Figure 4 shows the content (weight%) of metals other than chromium (non-chromium metal) on the horizontal axis, and the amount of wall thickness reduction (crane) on the vertical axis (logarithmic scale). Figure 0 shows the relationship between the content of non-chromium metal and the amount of wall thickness reduction in each specimen. Good ones (invention alloys) with a wall thickness reduction much smaller than 0.5N, ■~■ are outside the first alloy composition and have a wall thickness reduction of 0.5~
10n (comparative alloy), and V~ indicates a material other than the second alloy composition with a somewhat large wall thickness reduction of about 0.5 to 1.0 tm (comparative alloy). Also, the mouth shows magnesia chromia (contrast material).

Note that X indicates the range of the optimum weight ratio of the added metal.

Each column in the table is, from left to right, specimen sample-9.
Corresponding points on the graph in Figure 4, chromium content (wt%)
, content of non-chromium metals (wt%), content of additional metals (wt%), amount of wall thickness reduction on one side of the sample after testing (Tsuru)
It shows.

As can be seen from this table, with some exceptions, the reduction in wall thickness of chromium alloys or chromium alone is orders of magnitude smaller than that of magnesia and chromia, especially in the first and second cases.
If the alloy composition of , that is, the content of non-chromium metal in the chromium alloy is 3Qwt% or less, the amount of wall thickness reduction is 0.3fi.
It can be seen that the following is true.

It can also be seen that the second alloy composition has less wall thickness reduction than the first alloy composition, and is superior in corrosion resistance and erosion resistance.

In the above embodiment, both the furnace wall 17 of the melting furnace 7 and the inner wall 19c of the slag absorbing section are made of the fireproof wall member 18. However, the fireproof wall member 18 is used in the part where the molten slag comes into direct contact, that is, the inner wall 19c. Only the slag bot 9a and the slag outlet 9b may be used.

In addition, in the above embodiment, the joining rib 2 of the refractory alloy VI20 is
Although Oa has a trapezoidal shape in cross-section, it may also be formed in this shape.

Further, in the above embodiment, the composition of the fireproof alloy plate 20 was the first alloy composition, but this is the second alloy composition.

That is, it contains 0 to 30% of one or more of W, Mo, Nb, Ta, and V, and further contains Zr, Hf, and Y.

It may also be a chromium alloy containing 0 to 5% of one or more of Ce and La, with the remainder being chromium and unavoidable impurities; in this case, the adhesion of the film self-generated on the surface of the fireproof alloy plate 20 increases. As shown in the experimental results, the corrosion resistance and erosion resistance can be further improved compared to the first alloy composition.

In addition, as can be seen from the excellent alloy ■ (Sample Arashi 1) in the above experimental results, chromium alone has sufficient corrosion resistance and erosion resistance, so the composition of the heat-resistant alloy plate 20 in the above example is chromium. Chromium alone may be used instead of the alloy composition.

In addition, the refractory alloy plate 20 can be used as a high-performance, long-life metal heat-resistant member in place of refractories, and in this case, it is economically preferable to use it in the as-cast state; It is also possible to manufacture and provide a large-sized member by conventional rolling or press forging together with the capsule sheath material conventionally employed in boat fishing.

Furthermore, in the above embodiment, a combination of refractory bricks and refractory alloy plates was shown as the refractory material constituting the furnace wall.
The refractory may be composed only of a refractory alloy plate.

Further, in the above embodiment, a swirling flow melting furnace was used as an example, but the high-temperature processing apparatus for substances of the present invention is of course not limited to this, and in short, the processing apparatus for processing high-temperature molten oxides, etc. It can be applied to any indoor wall.

〔Effect of the invention〕

As described above, according to the high-temperature processing apparatus for substances according to the present invention, the inner wall of the processing chamber is made of a refractory metal member, and the refractory metal member is made of chromium alone or contains W, Mo, etc. in chromium.
, Nb, Ta, V or more at a weight ratio of 30%
Since the chromium alloy contains the following content, the refractory metal member will self-generate a film in a high temperature atmosphere.
This film also prevents contact between the refractory metal member itself and the molten slag. Further, by covering the surface of the refractory brick with a refractory metal member, contact between the refractory brick and the molten slag can be avoided. As a result, damage caused to the inner wall of the processing chamber due to corrosion or erosion can be greatly reduced, and the life of the inner wall can be greatly extended. As a result, the frequency of repair of the device can be reduced, which has the effect of reducing operating costs and equipment costs.

[Brief explanation of the drawing]

Figures 1 to 3 show incinerated ash 1 according to an embodiment of the present invention.
It is a diagram for explaining a coal ash melting processing device, and the first
2 is a sectional view showing the melting furnace of the processing device, FIG. 3 is a perspective view showing the structure of the fireproof wall member used in the melting furnace, and FIG. 4 is a perspective view showing a modification of the joint structure between the fireproof alloy plate and the refractory brick of the fireproof wall member, and FIG. 4 is a graph showing the experimental results that provide the basis for the effects of the present invention. 1 is a melting processing device (high temperature processing device), 2 is a melting furnace (processing chamber), 9C is an inner wall of a slag storage section, 17 is a furnace wall (inner wall of a processing chamber), 18 is a refractory wall member, 19 is a refractory brick, 20 is a heat-resistant alloy plate (heat-resistant metal member). Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a high-temperature processing device for materials in which the material is incinerated or melted in a processing chamber whose inner wall is made of refractory material, the refractory material is used at least in the part of the inner wall of the processing chamber that is in direct contact with the high-temperature material or the high-temperature atmosphere. The composition of the refractory metal member is chromium alone or a chromium alloy containing one or more of W, Mo, Nb, Ta, and V in a weight ratio of 30% or less. Features: High temperature processing equipment for substances.