JP2700064B2 - Fire resistant material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a process for producing high-temperature slag having strong corrosion and erosion, such as blast furnace slag, converter slag, sewage sludge melting slag, and industrial waste incinerator melting slag. The present invention relates to a refractory member used for a container, and more particularly to a refractory brick in which a member made of chromium or a chromium alloy is greatly improved in corrosiveness and erosion at a high temperature as compared with a refractory brick alone.

[Conventional technology]

Conventionally, various refractory bricks made of a mixture of Al ₂ O ₃ , SiO ₂ , SiC, MgO, CaO, Cr ₂ O ₃ and the like are used as linings in blast furnaces, converters, electric furnaces, and various types of hot metal treatment furnaces of steelworks. Used. However, refractory bricks are significantly corroded and eroded by the slag, especially in the area where a mixture of various oxides called slag generated as a result of hot metal treatment comes into contact with the furnace wall, and it is necessary to frequently replace refractory bricks. .

In addition, in sewage sludge melting treatment furnaces and the like, SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, P ₂ O ₅ and various oxides contained in the treated molten slag, especially in the furnace hearth, The refractories in contact with the slag are significantly corroded and eroded.

For this reason, MgO.Cr ₂ O ₃ refractories, which are considered to have the best corrosion resistance, have been used for conventional furnace wall members.

[Problems to be solved by the invention]

However, even if such a refractory which is considered to have the most corrosion resistance is used, there is a problem that its life is extremely short, several weeks.

In other words, the dissolution reaction of a solid into a liquid, such as the mechanism of erosion of refractories by molten slag, is governed by either the interface reaction rate control or mass transfer through the interface reaction layer, that is, diffusion control. It is thought that there is. It is said that the reaction between the refractory and the molten slag is mainly due to the latter diffusion control.

For example a typical Al ₂ O ₃ · SiO ₂ based refractories, typical slag having a composition CaO, the mechanism of the reaction to undergo corrosion and erosion by _{SiO 2 · Al 2 O 2 ·} MgO -based slag, and refractory The interdiffusion of refractory constituent element ions and slag constituent element ions is the rate-determining step through the reaction layer generated between the slag and the boundary layer formed at the interface between the two, and the concentration difference on both sides of the boundary layer is limited. It is said to be the driving force for the reaction. Therefore, the erosion rate increases as the solubility of the refractory constituent elements in the molten slag increases, as the thickness of the boundary layer decreases, and as the temperature increases.

Here, when looking at the composition of blast furnace slag and sewage sludge slag, they all consist of a mixture having a basic composition of SiO ₂ , Al ₂ O ₃ , CaO, Fe ₂ O ₃ , and a small amount of TiO ₂ , MnO, MgO, P ₂ O
_{5, Na 2 O, K 2} O and other corrosive S, contains a like V ₂ O _5. Therefore, basically, the refractory and the molten slag are almost the same type of oxide as the main constituent components, and thus the erosion becomes faster as the solubility of each constituent element in the molten slag is larger.

Also, the boundary layer shown here is almost always a locally viscous liquid phase near the solid surface, so that fresh slag flows and contacts constantly like a blast furnace slag gutter. If the slag itself is constantly stirred, the formation of a boundary layer cannot be expected, so that even magnesia chromia (MgO · Cr ₂ O ₃ ) erodes more and more due to the above-mentioned corrosion and erosion mechanism. Will be. As a result, any existing refractory has a very short life.

The present invention has been made to solve such a problem, and is hardly corroded or eroded even when it comes into contact with highly corrosive and corrosive slag in a high-temperature combustion gas atmosphere. It is an object of the present invention to obtain a fire-resistant wall member whose life can be significantly extended by using it as a member.

[Means for solving the problem]

The refractory member according to the present invention has a refractory surface directly in contact with a high-temperature and corrosive atmosphere made of a refractory metal member, and the refractory metal member has a composition of chromium alone, or W, Mo, Nb, Ta in chromium. , V, a composition comprising a chromium alloy containing 30% or less by weight of one or more kinds of V. The refractory member according to item 2 further comprises 0.05 to 5% by weight of the chromium alloy. Or one or more of Zr, Hf, Y, Ce, and La.

Here, the refractory member means an inner wall of a processing container for a high-temperature substance or a flow path for a high-temperature substance, such as a tub.

Hereinafter, the reason why the above configuration is employed in the present invention will be described in detail.

The present inventor, in order for the refractory member to have high corrosion resistance and erosion resistance in a high-temperature combustion gas atmosphere as described above,
Avoids self-generation of high-temperature film that is difficult to peel and separate during operation of the melting furnace, etc., and avoids direct contact with molten slag.
In addition, the inventors considered that it is desirable to have a function of self-repairing even if a crack occurs in the film. And as a result of studying the reactivity of various metal materials with various slags with a focus on metal materials as having such a function, as a new refractory metal member that does not exist at all in heat-resistant members currently in practical use, Chromium and chromium-based alloys have been found to be very effective. As a result of experiments at the actual plant, the chromium alloy is compared with the magnesia-chromia refractory, which has the longest life among various existing refractories.
It proved to be a revolutionary metal material that replaces conventional refractories with a lifespan more than 100 times longer.

In order to extend the life of this refractory metal member, it is desirable that the above-mentioned film is gradually formed and that the film is always thinly adhered to the base material. To satisfy the demands of. Further, if one of W, Mo, Nb, Ta, and V, which is an element having an atomic radius larger than that of chromium and has heat resistance higher than that of chromium, alone or in combination of two or more of these metals, is added to chromium. I also found it to be effective. However, since these elements are easily oxidized and volatilized at high temperatures, the addition of a large amount rather deteriorates the erosion resistance and shortens the life of the material. Therefore, based on the results of the performance test described later, the upper limit of the single or composite addition is set to 30 wt%.

As a result, the specific composition of the refractory metal member is W, Mo, Nb,
A chromium alloy (first alloy composition) containing one or two or more of Ta and V in an amount of 0 to 30% by weight, with the remainder comprising chromium and unavoidable impurities can be used.

Further, in order to make the film formed on the refractory metal member of the first alloy composition more adherent, that is, hard to peel off, one of Zr, Hf, Y, Ce, and La may be used alone or in combination. It has been found that more than one kind may be added in combination. The effect of this additional addition was not changed irrespective of whether it was used alone or in combination, and the upper limit was set to 5 wt% based on the results of actual tests described later.

As a result, the further composition of the refractory metal member is W, Mo, Nb,
Contains 0 to 30 wt% of one or more of Ta and V, and Z
A chromium alloy (second alloy composition) containing 0 to 5 wt% of one or more of r, Hf, Y, Ce, and La, and the remainder comprising chromium and unavoidable impurities.

In addition, the heat-resistant alloy mentioned here is only required to have a function of forming an oxide film of a self-forming type and a self-healing function type during use at a high temperature as described above. This has been proved experimentally. Therefore, the composition of the refractory metal member may be chromium alone instead of the first and second alloy compositions.

And, as a result of the above-mentioned earnest research,
It has been conceived that corrosion or erosion can be prevented by forming a flow path to the furnace wall or high-temperature substance using such a metal material, or covering the exposed surface of the refractory brick exposed inside the furnace. The present invention has been accomplished.

[Action]

In the present invention, the refractory surface portion directly in contact with a high-temperature and corrosive atmosphere or substance is constituted by a refractory metal member, and the refractory metal member is composed of chromium alone or a chromium alloy of the first and second alloy compositions. The refractory metal member avoids direct contact with the molten slag by self-generating a film that is difficult to peel and separate in a high-temperature combustion gas atmosphere, and furthermore, when a crack occurs in the film. Will self-repair, thereby protecting the refractory metal member itself. The refractory brick is protected by the refractory metal member by covering a predetermined side surface of the refractory brick with a refractory metal member and exposing the coated surface to a high-temperature and corrosive atmosphere for use.
Corrosion and erosion are suppressed. Therefore, when this refractory wall member is used for a furnace wall or the like, the life of the melting furnace or the like can be significantly improved.

〔Example〕

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

FIG. 1 (a) is a diagram showing a cross-sectional structure of a refractory member according to one embodiment of the present invention. In the drawing, reference numeral 1 denotes a refractory brick 2 for a refractory member used for a furnace wall of a melting furnace or the like. And a refractory alloy plate 3 joined to the surface to protect the surface from a high-temperature atmosphere. For joining the refractory brick 2 and the refractory alloy plate 3, a joining rib 3 a having a trapezoidal cross section is formed on the back surface of the refractory alloy plate 3, and the refractory brick 2 is joined to the back surface of the refractory alloy plate 3. This is performed by forming the ribs 3a for use so as to be embedded in the bricks 2.

The refractory brick 2 is made of a mixture of Al ₂ O ₃ , SiO ₃ , SiC, MgO, CaO, Cr ₂ O _{3 and the} like, and the refractory alloy plate 3 is made of W, Mo, Nb,
The first alloy composition contains 0 to 30% by weight of one or more of Ta and V or two or more of these metals, and the remainder is chromium and unavoidable impurities.

 Next, the operation and effect will be described.

As described above, in the present embodiment, one surface of the refractory brick 2 is coated with the refractory alloy plate 3 and the coated surface is exposed in a high-temperature and corrosive atmosphere for use. Can be protected from corrosion and erosion.

In addition, the composition of the refractory alloy plate 2 is one of W, Mo, Nb, Ta, V, or two or more of these metals, which is a first alloy composition containing 0 to 30% by weight, with the balance being chromium and unavoidable impurities. A self-generated film on the surface of the refractory alloy plate 3 that is difficult to peel and separate at high temperature to avoid direct contact with the molten slag, and to self-repair even if a crack occurs in the film. Becomes Thereby, the refractory alloy plate 3 itself can be protected. As a result, a furnace wall member having excellent corrosion resistance and erosion resistance can be obtained.

Next, the results of tests on the erosion resistance and corrosion resistance of the chromium and the chromium-based alloy, which are the basis of the effect of the present invention, using an actual plant will be described with reference to the table on the separate sheet and the graph in FIG.

The test consisted of a chromium-based alloy specimen (sample Nos. 1 to 38) with the composition shown in the table and a magnesia-chromia brick (sample N), which is said to be the most corrosion resistant of this type of refractory.
o.39) was used. The test method is to melt these test pieces in vacuum and cut the test pieces from the ingot into a fluidized bed type heating furnace that continuously supplies a molten synthetic slag having the following composition range at a temperature of 1500 ° C. For 200 hours in a molten slag. The corrosion resistance and erosion resistance were evaluated by measuring a small thickness (one side) of the test piece after the test.

Slag _{composition; SiO 2 = 10~40%, Al} 2 O 3 = 5~20% Fe 2 O 3 = 0~20%, CaO = 10~40% TiO 2 = 0.2~3%, P 2 O 5 = 3 ~25% MgO = 1~7%, except chromium _{Na 2 O = 0.3~5% K 2} O = 0.2~3% S = 0.3~5% V 2 O 5 = 0.2~3% Figure 2 the horizontal axis The metal (non-chromium metal) content (% by weight) is plotted on the vertical axis (logarithmic scale), and the thickness reduction (mm) is plotted on the vertical axis. This shows the relationship. ~
as well as Means that the wall thickness reduction amount of the first and second alloy compositions is 0.
Excellent product (invention alloy) much smaller than 5mm, Is a material having a large thickness reduction of 0.5 to 10 mm outside the first alloy composition (comparative alloy), Indicates a material (comparative alloy) having a slightly large thickness reduction of about 0.5 to 1.0 mm outside the second alloy composition. Also, Indicates magnesia chromia (comparative material).

Each column in the table indicates the sample N of the test piece in order from the left.
o, corresponding points on the graph of Fig. 2, chromium content (% by weight), non-chromium-added metal content (% by weight), additional added metal content (% by weight), The thickness reduction (mm) is shown.

As can be seen from this table, the thickness reduction of the chromium alloy or chromium alone is orders of magnitude smaller than that of magnesia / chromia, and especially the first and second alloy compositions,
That is, when the content of the non-chromium metal in the chromium alloy is 30% or less, the thickness reduction amount is 0.3 mm or less.

Also, it can be seen that the second alloy has a smaller amount of thickness reduction than the first alloy, and is superior in corrosion resistance and erosion resistance.

Further, as can be seen from the superior alloy (sample No. 1) of the above experimental results, since chromium alone has sufficient corrosion resistance and erosion resistance, the composition of the heat-resistant alloy plate 3 is not a chromium alloy composition, It may be chromium alone.

Further, the alloy of the present invention can be used as a high-performance, long-life metal heat-resistant member in place of a refractory. In this case, it is economically preferable to use the alloy as cast,
Some long-sized members can be manufactured and provided by ordinary rolling or press forging together with capsule materials and sheath materials generally used conventionally.

Hereinafter, specific applications of the fire-resistant wall member of the present embodiment will be described.

FIG. 3 is a sectional view showing a structure of a melting furnace for industrial waste using the fire-resistant wall member. In the drawing, reference numeral 5 denotes a vertical vertical melting furnace, in which a fuel inflow portion 8 is flange-connected to an upper end portion of a cylindrical furnace body 7 formed by a combustion chamber 6, and a slag housing portion 9 is connected to a lower end portion. An exhaust gas outflow portion 7a is formed at a lower portion of the furnace body 7.

Here, 8a is a burner tile formed in the fuel inflow section 8, 10 is an auxiliary burner mounted in the inflow section 8,
A solid-gas two-phase flow supply pipe 11 and a fuel supply pipe 12a are connected to the auxiliary burner 10. 13 is a solid-gas two-layer flow supply pipe 11
The ash supply pipe 14 from the ash supply device and the combustion air supply pipe 15 are connected by a T-tube type ejector connected to the ash supply device.
Reference numerals 9a, 9b and 9c denote a slag pot, a slag port and an inner wall of the slag absorbing portion 9, respectively. 7b is an iron shell constituting a furnace shell, and 16 is a cooling jacket formed on the outermost periphery of the iron shell 7. , 16a, 16b are cooling water inlets and outlets of the jacket 16, respectively, and 17 is a furnace wall formed inside the steel shell 7b.

Here, a melting furnace 5 exposed to a high-temperature and corrosive atmosphere is used.
Of the furnace wall 17 and the inner wall 9c of the slag absorber 9
Is constructed by lining the fire-resistant wall member 1 of this embodiment. The refractory wall member 1 does not constitute the entire inner wall of the furnace, but may include, in particular, only a portion in direct contact with the molten slag, for example, only the slag pot 9a and the slag port 9b of the inner wall 9c of the slag absorbing section.

In such a melting furnace, coke oven gas and combustion air preheated to a predetermined temperature are blown from the auxiliary burner 10 into the melting furnace 5 and burned.
Hold at ~ 100 ° C higher. For example, keep it at 1550 ° C for lime ash and 1400 ° C for sewage sludge incineration ash.
In this state, when a predetermined amount of air is transported from the ash supply pipe (not shown) to the ejector 13, the ash is uniformly mixed into the combustion air in the ejector 13, and the combustion air and the ash are mixed. The two-phase gas flow is given a strong swirling flow by the swirling blades of the burner 10 and is uniformly injected into the combustion chamber 6.
As a result, the ash draws a spiral and the centrifugal force causes
It is rapidly burned while colliding with 17, and then is turned into molten slag and falls into the slag pot 9a, and the slag port 9b
Is discharged from On the other hand, the exhaust gas passes through the outflow passage 7a,
It is discharged to the outside via a heat exchanger, a dust collector, etc., not shown.

Here, when melting the ash, since various substances are contained in the ash, in the conventional apparatus, these substances easily react with the furnace wall and erode, and the life of the part is short. There was a problem. On the other hand, in this example, since the furnace wall 17 of the melting furnace 5 is configured by the refractory wall member 1,
The heat-resistant alloy plate 3 is peeled off in a high-temperature combustion gas atmosphere.
This prevents self-generation of a coating that is difficult to be separated and prevents direct contact with the molten slag, and even if a crack occurs in the coating, the coating is self-repaired.

Therefore, the heat-resistant alloy plate 3 itself is protected from corrosion or erosion by the film, and the refractory brick 2 is protected by the heat-resistant alloy plate 3, so that the life of the furnace wall can be greatly extended. As a result, the frequency of repair can be reduced, so that operating costs and equipment costs can be reduced.

Note that, in the above embodiment, a combination of a refractory brick and a refractory alloy plate was shown as a refractory constituting a furnace wall.
The refractory may be composed only of the refractory alloy plate.

Further, in this example, the case where the refractory member of the present invention is used in a swirling flow type melting furnace has been described, but the application of the refractory wall member is not limited to this melting furnace. Further, the refractory member of the present invention can be applied not only to a furnace wall but also to a flow path of a high-temperature substance such as a tub.

In the above embodiment, the joining rib 3a of the refractory alloy plate 3 is used.
Is formed in a trapezoidal shape in cross section, but may be formed in a rectangular shape in cross section as shown in FIG. 1 (b), and a hole 3b for preventing displacement is formed in a part of the rib 3a. In addition, the connection structure between the refractory metal plate 3 and the refractory brick 2 may be variously modified in addition to the structure of the above-described embodiment. For example, a locking piece is provided on the metal plate, and this is locked to the refractory brick. Alternatively, it is also possible to bond using an adhesive.

〔The invention's effect〕

As described above, according to the refractory member according to the present invention, the refractory surface portion that is in direct contact with a high-temperature and corrosive atmosphere or substance is constituted by a refractory metal member, and the composition of the refractory metal member is chromium alone or W in chromium. , Mo, Nb, Ta, V one or more of the chromium alloy containing at least 30% by weight of the content of the chromium alloy, the surface of the refractory metal member,
In a high-temperature combustion gas atmosphere, a film that does not easily peel off or separate occurs, thereby protecting the refractory metal member itself. In addition, the refractory brick is coated with a predetermined side surface by using a refractory metal member, and the coated surface is exposed to a high-temperature and corrosive atmosphere to be used, so that the refractory brick is protected by the refractory metal member for corrosion and erosion. Can be suppressed. Therefore, when this refractory wall member is used for a furnace wall or the like, there is an effect that the life of the melting furnace or the like can be significantly improved.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing a configuration of a refractory member according to one embodiment of the present invention, and FIG. 1 (b) shows a modified structure of a joint structure between a refractory alloy plate and a refractory brick in the above embodiment. FIG. 2 is a graph showing experimental results which are the basis of the effect of the present invention, and FIG. 3 is a sectional configuration of a melting furnace for industrial waste using the refractory member of the present invention as a furnace wall member. FIG. In the figure, 1 is a refractory member, 2 is a refractory brick, and 3 is a refractory alloy plate (refractory metal member). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] In a refractory member constituting a wall surface against a high-temperature substance, a refractory surface portion directly in contact with a high-temperature and corrosive atmosphere or a substance is composed of a refractory metal member, and the composition of the refractory metal member is made of chromium alone. A refractory member having a composition or a chromium alloy containing one or more of W, Mo, Nb, Ta, and V in chromium at a weight ratio of 30% or less. 2. The method according to claim 1, wherein the chromium alloy contains 0.05 to 5% by weight of Zr, H.
The refractory member according to claim 1, wherein one or more of f, Y, Ce, and La are contained.