JP2842174B2 - Brick for coke oven, method for producing the same, and furnace wall structure of coke oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reforming a refractory brick used in a furnace body of a kiln and a furnace wall structure of a coke oven using the same. More specifically, by applying a secondary processing to the existing bricks, aims to improve the performance of bricks, goodwill for coke oven with enhanced furnace wall structure of the coke oven
And its manufacturing method, and coke using the brick
The present invention relates to a furnace wall structure of a furnace .

[0002]

Recently, coke oven along with the size of the steel manufacturing facilities are large, but the aim of improving productivity, further energy saving and NO _x reduction aspect coking chamber for shortening the carbonization time from There is a tendency to reduce the thickness of the furnace wall,
There is a demand for dense and high thermal conductive silica brick. In the following, the "brick" will be described using a silica brick as an example.

On the other hand, in a coke oven, carbon derived from dry distillation gas adheres to the inner wall surface of the oven during operation, and a strong carbon adhered layer is formed. Therefore, a dense brick to which carbon is unlikely to adhere is required.

In order to cope with such a situation, various proposals have conventionally been made on a method for producing a dense brick, a treatment method for densifying the brick, or a method for maintaining the cleanness of the brick surface.

In the production of dense bricks, for example, dense silica bricks, a method of adding an oxide-based material such as CaO, TiO ₂ , MgO, or blending a non-oxide such as SiC, SiN, etc. in the firing step There are methods for promoting oxidation. However, in these methods, unevenness in firing tends to occur, and even if densification can be achieved, since the fire resistance and the softening point under load are reduced,
Sufficient performance cannot be maintained. In addition, the adjustment of the pore distribution is insufficient with this method.

On the other hand, as a treatment method for densifying the silica brick, there are a method of appropriately applying a substance to the surface of the brick in order to seal the pores in the surface area of the brick and a method of impregnating the pores in the brick with the substance as appropriate. .

As the former method, for example, Japanese Patent Publication No.
There is a method of treating with a coating material containing fly ash as a main component described in 27873, or a method of providing a glaze layer made of crystalline glass as described in JP-A-59-174585. Similarly, a method for providing a glaze layer is disclosed in
There is a method described in JP-A-63-236783. Each of these surface treatment materials is a low-melting material containing alkali, ZnO 2, CaO 2 and the like, and thus rather deteriorates the fire resistance of the silica brick as a base material. In addition, since the surface layer contains a liquid phase, it promotes the adhesion of carbon, and wears due to friction with the coke cake when it is discharged from the kiln, so that only a transient effect can be expected.

As the latter impregnation method, for example, magnesia-dolomite bricks may be impregnated with wax to prevent moisture absorption. It is also a well-known method to impregnate coal tar from the viewpoint of improving corrosion resistance. There is also known a method of impregnating with colloidal silica (silica sol) and performing heat treatment so that SiO ₂ remains in pores. However, its content is about 20% by weight with respect to the weight of the brick to be treated, and the filling amount is smaller than the permeation amount of the solution, and in fact, a sufficient effect cannot be obtained.

Although it is theoretically possible to impregnate alumina sol, Al ₂ O ₃ itself is a chemical component equivalent to coal ash for silica brick in a coke oven. From the viewpoint of long-term use, it has a low melting point or SiO _2. Undesirably leads to the promotion of cristobalite. The conventional impregnation method is a method of immersing in a solution or degassing after immersion. However, it has been found that immersion unevenness is likely to occur depending on the physical properties of the solution.

Next, as a method for preventing the adhesion of carbon and maintaining the cleanliness of the brick surface, there is a carbon removal method. For example, Japanese Patent Application Laid-Open No. 61-231088 discloses a method of burning and removing carbon using a special nozzle. There is also a method of shaving off with a sandblaster. However, these are effective in removing the adhered carbon itself, but secondary to the damage of the base material brick, which impairs the robustness of the furnace in the long term. As described above, the various means conventionally proposed are not yet sufficient, and from the practical point of view, means that are particularly robust and can extend the life are required.

In general, filling the pores with an oxide and densifying the pores is a treatment that impairs spalling resistance and is incompatible with improving strength. However, if the microstructure can be changed in the direction of making the pore distribution pores, a state is obtained in which densification and spalling resistance are simultaneously satisfied and carbon is hardly generated. Also, if the impregnating substance can be given a releasing action, it can be used semi-permanently as furnace wall brick,
Although the economics are significantly improved, no such method is currently established.

[0012]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to form a wall mainly for a carbonization chamber of a coke oven which has good heat transfer characteristics with respect to carbonization, suppresses carbon deposition during operation, and is strong and robust. To provide a densified silica brick and a method for producing the same, and a furnace wall structure composed of the same.

Here, the problems of the furnace wall structure using the conventional silica brick are summarized as follows. (i) Densification by the addition of additives causes deterioration of other properties such as fire resistance, and the adjustment of pore distribution is insufficient. (ii) The method of sealing the surface of the brick by coating the surface with an appropriate substance has a temporary effect, and rather has a large adverse effect. (iii) In the method in which pores are sealed by impregnation, the amount of residual components is small, and the required pore reduction cannot be achieved.

In particular, the following problems are seen in the conventional brick impregnation treatment. By simply immersing in the impregnating solution, the amount of residual components in the brick is small, and when a large amount of the residual components is mixed in the impregnating solution, sedimentation is remarkable, and the required pore reduction cannot be achieved. Even if the sedimentation in the impregnating liquid is reduced by adjusting the particle size of the residual component, the liquid is extremely agglomerated, becomes a highly viscous liquid, and the impregnation becomes insufficient. When the brick is immersed and degassed and decompressed, the air in the brick is significantly degassed and uneven impregnation tends to occur. To prevent this, it is necessary to perform degassing for a long time.

[0015]

Accordingly, as a result of various studies by the present inventors, the pores of existing silica bricks are impregnated with ceramic fine particles by a new method and procedure to make the apparent porosity of silica bricks. It has been found that by reducing the number of furnaces, a robust furnace wall structure with less operation trouble can be obtained. In particular, not only the conventional solution impregnation but also the impregnation of a large amount of fine particles achieves efficient sealing of pores.

Further, Cr ₂ O ₃ whose particle size has been adjusted as fine particles
By adding CaCO ₃ powder and CaCO ₃ powder, it was also found that the pore size distribution of the pores could be achieved without impairing the fire resistance of the base material, so that spalling resistance was not impaired.
Here, it is effective to use a silica sol and / or zirconia sol whose viscosity has been adjusted as a solution to which fine particles are added and dispersed.

Accordingly, the gist of the present invention is as follows.
(I) A silicon- and / or zirconium-based impregnating liquid having a viscosity of 50 centipoise or less at room temperature to which one or two kinds of chromium oxide powder and calcium carbonate powder having an average particle diameter of 0.01 to 1.0 µm are added. 5-100mm
A method for producing a silica brick for a coke oven, wherein the silica brick is impregnated under Hg atmosphere pressure; (ii)
Under the atmospheric pressure of 2.5-100mm of mercury, the brick
Chromium oxide having an average particle size of 0.01 to 1.0 μm
At room temperature with one or two calcium carbonates added
Silicon impregnating liquid having a viscosity of 50 centipoise or less
And / or impregnated with a zirconium-based impregnation liquid
Bricks for coke ovens, characterized in that: (iii)
The coke oven wall structure is characterized in that at least a part of the wall surface of the carbonization chamber is made of silica brick produced by the above method.

[0018]

Next, the manufacturing process of the SiO ₂ brick for a coke oven according to the present invention, that is, the silica brick, will be explained, and the contents of the present invention will be clarified together with the function thereof. The composition of the brick used as the base material in the present invention is not particularly limited, but preferably the one having an apparent porosity of 11 to 30% is used. When the apparent porosity is less than 11%, the spalling resistance decreases even when impregnated by the method of the present invention, and the apparent porosity is reduced.
If it exceeds 30%, the impregnation efficiency is reduced, and the desired effect may not be sufficiently obtained.

A silicon-based or zirconium-based impregnation liquid in which the brick is dispersed with one or two kinds of fine particles selected from chromium oxide powder and calcium carbonate powder;
That is, it is impregnated with a silicon-based or zirconium-based liquid binder. At this time, as the fine particles to be dispersed in the impregnating liquid, a chromium oxide powder or a calcium carbonate powder alone or a mixed powder thereof is used.

Chromium ions form a high-viscosity melt even if they react with SiO ₂ in the brick, and therefore have little adverse effect on load softening. Also, calcium ions, shows the effect of the reaction of the SiO ₂ has a property of tridymite the SiO _2, increased resistance to rapid heating-rapid cooling.

In particular, according to a preferred embodiment of the present invention,
In a colloid particle region or a submicron particle region, i.e., a solution in which an oxide or carbonate having a fine particle diameter and a particle diameter different from the pore diameter are dispersed in water is penetrated into the pores of the brick under reduced pressure and degassed. This is a method for improving the properties of bricks that reduces the pore distribution.

The large oxide or carbonate of the particles to be impregnated has a role of sealing the colloid particles in the pores because of its size.
When mixed as described above, the encapsulating effect is greater than when no additive is added.

The average particle size of these fine particles is 0.01
1.01.0 μm. Desirably the largest particle is 5 μm
It is better to be less than. When the average particle size is larger than 1.0 μm, it is difficult to smoothly penetrate into pores of the silica brick, so that only the surface layer is completely penetrated and pores having a diameter of 30 μm or less cannot be penetrated. If water is used as the dispersion medium and the average particle size is smaller than 0.01 μm, the particles will be strongly agglomerated when dispersed, making it difficult to efficiently disperse them in the binder liquid.

In the case where only conventional silica sol (average particle size of the dispersoid) is impregnated into a brick without using these fine particles, the impregnation is merely a liquid impregnation.
Substantial packing by particles is low.

As a dispersion medium for dispersing the fine particles,
A silicon-based or zirconium-based impregnating liquid having a viscosity at room temperature of 50 CP (centipoise) or less, that is, a water-based (H ₂ O) liquid binder containing a silicon compound or a zirconium compound is used. Many organic binders have low vapor pressures and are not practical. In addition, there are also those with a high viscosity of more than 50CP, and they are not practical for viscosity adjustment.

By using a silicon-based or zirconium-based liquid binder, Si or Zr having high fire resistance can be supplemented, which contributes to densification. Examples of such useful liquid binders are silicone oils (diluted with organic solvents if necessary), silica sols, and aqueous sodium silicate (eg, water glass) and zirconia sols.

In particular, in the case of zirconia sol, colloid particles
(ZrO ₂ ) has a larger mass than SiO _{2 in} the case of silica sol,
Since the particle size is large, the pores in the brick structure are efficiently impregnated.

Aqueous liquids such as silica sol and zirconia sol have a high vapor pressure and form water of crystallization and adhesion during the evaporation of water, so that the water is completely removed in the next drying step. Be careful.

Such a liquid binder has a viscosity at room temperature.
It is within the range of 50 centipoise (cp) or less. If the viscosity is too high, dilute it with an appropriate diluent (organic solvent, water) to reduce the viscosity.

The viscosity of the impregnating liquid (25 ° C.)
It should be adjusted to 25 CP or less and 2.5 CP or more, preferably 15 to 5 CP. Therefore, it can be arbitrarily adjusted depending on the amount of the added fine particles. The blending amount of the fine particles is not particularly limited, but usually 60% by weight or less is uniformly mixed with the dispersion medium. If it exceeds 60%, the viscosity of the prepared impregnating liquid increases, and it may be difficult to perform a sufficient amount of impregnation. If desired, small amounts of other components may be present in the impregnation liquid. Examples of other components that can be added include organic dispersants (eg, dextrin).

The impregnating liquid thus prepared is impregnated in a brick under vacuum. This impregnation is performed by charging the impregnating liquid and the brick in a vacuum tank and deaeration with a vacuum pump, or deaeration of the vacuum tank in which the brick has been previously charged, and then impregnating while maintaining the degree of vacuum. It can be carried out by introducing a liquid. The vacuum degree of the vacuum chamber before the impregnation liquid is set in the range of 2.5 to 100 mmHg (indicated by the height of the mercury column) using a manometer. Desirably, it is appropriate to keep it constant at 20 to 50 mmHg. If it exceeds 100 mmHg, impregnation of the liquid tends to be insufficient. If it is less than 2.5 mmHg, there is no problem in processing on a laboratory scale, but on a practical scale, it takes a long time to deaerate, which is not practical.

Therefore, ideally, once the gas is degassed to 20 mmHg, the impregnating liquid is injected into the tank, and a uniform impregnation treatment can be achieved if the degree of vacuum is within 50 mmHg at the completion of the injection.
Therefore, for example, the method of vacuum degassing in a state of being immersed in the solution in the tank cannot provide a sufficient effect in terms of uniformity of impregnation in the case of a brick having a large porosity. Air from bricks in this way, equivalent to traditional tar impregnation
Since the release of (gas portion) and the penetration of the liquid occur simultaneously in the same brick, the penetration of the micron to submicron particles is undesirably inhibited by foaming in the pores.

This impregnating treatment is performed so that the impregnating liquid permeates at least 10 mm or more from the surface layer of the brick. Normal temperature is sufficient for the impregnation temperature, but heating may be performed if desired. The impregnation time is usually one hour or more, and is adjusted according to the temperature and the size of the brick to be treated.

After the impregnation, the brick is taken out of the vacuum chamber and dried to remove volatile components such as a solvent in the impregnating liquid. Drying is desirably heat drying, but drying at room temperature is also possible depending on the type of solvent.

The silica brick produced by impregnation according to the method of the present invention is densified and has significantly improved thermal and mechanical properties as compared with untreated brick. By configuring the furnace wall structure, it is possible to form a robust coke oven wall structure of a coke oven with little carbon adhesion, high thermal conductivity. Furthermore, since the impregnated binder and calcium carbonate powder are thermally decomposed to form fine pores by raising the temperature at the start of the coke oven operation, the thermal shock resistance is kept good, and the spalling resistance is lowered. Absent.

Therefore, at least a part of the furnace wall structure of the coke oven carbonization chamber (for example, the middle area of the furnace wall of the carbonization chamber), and preferably all of the furnace wall structure is made of the silica brick selected by the method of the present invention, so that heat conduction is achieved. A coke oven wall structure is constructed that has good performance, has few troubles, has a significantly extended life, and does not require the removal of adhered carbon.

The method of the present invention comprises the steps of:
The present invention can be similarly applied to fused quartz brick, alumina-based, magnesia-based brick, and the like. In this case, the porosity can be further reduced by repeating the impregnation treatment and the heat treatment, but it goes without saying that the required porosity and the treatment cost corresponding to the effect are of course balanced.

Next, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

[0039]

【Example】

Example 1 Calcium carbonate powder having an average particle size of 0.1 μm,
Chromium oxide powder having an average particle size of 0.2 μm was uniformly mixed in a weight ratio of 1: 9, 18% of the mixed powder was mixed with 82% of a liquid binder shown in Table 1, and sufficiently stirred by ultrasonic vibration. The powder was dispersed uniformly and an impregnation liquid was prepared. In Table 1,
The values of specific gravity and viscosity are values after dilution.

[0040]

[Table 1]

From a silica brick having an apparent porosity of 21%, the diameter is
Cut out two types of test specimens, a 50 mm x 50 mm long cylindrical body and a 25 mm x 25 mm x 140 mm square rod, deaerate both test specimens to a degree of vacuum of 10 mmHg, and place them in this vacuum chamber. The impregnating liquid was introduced, and the impregnating liquid was permeated into the pores of the entire brick.
Thereafter, the substrate was immersed for 10 minutes while maintaining the degree of vacuum at 20 mmHg. Then take out the silica brick from the impregnating liquid, dry it with hot air,
An impregnated material was obtained.

The impregnated material thus obtained was further dried in a dryer at 100 ° C. for 10 hours for testing, and then the pore size distribution by a mercury intrusion method and the hot bending strength at 1000 ° C. were measured. did. Table 2 summarizes the measurement results.

As target values, an apparent porosity of 16 (%) or less, a cyclopore amount of 0.08 cc / g or less, and an average pore diameter of 10 μm or less were set. As can be seen from Table 2, when the silica brick is impregnated with the impregnating liquid in which fine particles of chromium oxide and calcium carbonate are dispersed according to the present invention, the apparent porosity, the amount of micropores, and the average pore diameter are larger than those of the untreated silica brick. All of them significantly decreased, and densification and pore formation of the structure were achieved.

[0044]

[Table 2]

[Embodiment 2] Example Ru of the present invention shown in Embodiment 1
n No.2 silica brick treatment material (impregnated treatment material using colloidal silica solution as binder, provided that the blending amount of chromium oxide powder is 17% by weight and calcium oxide powder is 1.9% by weight,
The viscosity of the impregnating liquid was changed by changing the concentration of the colloidal silica solids. ) And a commercial dense silica brick (apparent porosity 15.6%) were subjected to a heat cycle test. FIG. 1 shows the pore distribution of both test materials obtained by a series of impregnation treatments prior to the test.

In the heat cycle test, the temperature was 900 ° C. each.
The test was performed by vertically reciprocating a cylindrical brick specimen in two vertically connected cylindrical electric furnaces maintained at 400 ° C. and applying thermal shock.

Table 3 shows the results of visual observation of the surface of the test piece after 10 cycles of thermal shock for cracks.
Shown in In addition, as a conventional example, according to the method disclosed in JP-A-59-174585, results of the same test on a test material in which the surface of a silica brick is coated with a glaze layer made of a low-expansion crystalline glass are also shown. .

In the untreated conventional example, cracks were generated by thermal shock, whereas those impregnated by the method of the present invention were resistant to thermal shock and did not crack. Therefore, it can be seen that the method of the present invention produces silica brick having excellent thermal shock resistance. It was found that the coating of the surface coated with the low-expansion glaze layer of the comparative example was peeled off by the thermal shock and could not serve as the coating.

[0049]

[Table 3]

[0050] In coke ovens A in operation in Example 3 load factor 115% (oven volume 48.5 m ^3, 50 Gate) for transhipment repair of coke side end flue bottom, about 1.9 m ² size Then, the silica brick on the furnace wall was cut open, and after repair, a separate brick was replaced to repair the furnace wall. A silica brick impregnated by the method of the present invention (treated material b of Example 2) was applied as a replacement brick at this time, and the state of the wall surface was observed and evaluated for cracks and carbon adhesion during inspection of an empty kiln. The result
Table 4 shows the results when the conventional untreated silica brick was replaced with an apparent porosity of 18%.

[0051]

[Table 4]

As is clear from the above results, it was found that the impregnated steel according to the present invention had less carbon adhesion and less cracking during operation than the conventional silica brick.

[Embodiment 4] In the embodiment of the present invention shown in Embodiment 1,
Silica brick treated material according to Run No.4 (impregnated treated material using zirconia sol solution as binder, provided that the content of chromium oxide powder is 15% by weight, calcium oxide powder is 2.0% by weight, and the The same thermal cycle test as described above was carried out on the impregnating liquid by changing the viscosity.) And a commercially available dense silica brick (apparent porosity: 15.6%). FIG. 2 shows the pore distribution of both test materials obtained by a series of impregnation treatments prior to the test.

Table 5 shows the results of visual observation of the surface of the test piece after 10 cycles of thermal shock for cracks.
Shown in As a conventional example, results of a test material in which the surface of a silica brick is coated with a glaze layer made of a low-expansion crystalline glass according to the method disclosed in JP-A-59-174585 are also shown. Solution (c) is a mixture of 30% zirconia sol and 55% silica sol,
It is an impregnating solution adjusted to 12 to 15 cps.

In the untreated conventional example, cracks were generated by thermal shock, whereas those impregnated by the method of the present invention were resistant to thermal shock and did not crack. Therefore, it can be seen that the method of the present invention produces silica brick having excellent thermal shock resistance. It was found that the coating of the surface coated with the low-expansion glaze layer of the comparative example was peeled off by the thermal shock and could not serve as the coating.

[0056]

[Table 5]

[Example 5] In a coke oven A (a furnace capacity of 48.5 m ³ , 50 gates) operating at a load factor of 100%, an area of about 3.1 m ^{2 was used} for repairing transhipment at the end flue bottom on the coke side. Then, the silica brick on the furnace wall was cut open, and after repair, a separate brick was replaced to repair the furnace wall. As a replacement brick at this time, a silica brick impregnated by the method of the present invention [the treatment material of Example 4 (b)] was applied, and the state of the wall surface was observed and evaluated for cracks and carbon adhesion at the time of inspection of an empty kiln. The result
Table 6 shows the results when the conventional untreated silica brick was replaced with an apparent porosity of 18%.

[0058]

[Table 6]

As is clear from the above results, it was found that the impregnated steel according to the present invention had less carbon adhesion and less cracking during operation than the conventional silica brick.

[0060]

The impregnation treatment according to the present invention produces a reinforced silica brick having an apparent porosity lower than that of an untreated silica brick, significantly densified, and having a high hot strength. Can be. Moreover, the resulting silica brick has a reduced pore diameter due to the impregnation process,
Despite the impregnation treatment, the thermal shock resistance is higher than that of the untreated product, and the spalling resistance is improved. Therefore, according to the present invention, a silica brick for forming a furnace wall of a coke oven carbonization chamber, which is dense, has low carbon adhesion, has good thermal conductivity, has high strength and long life, and has excellent spalling resistance. It can be easily manufactured. As a result, the operating efficiency of the coke oven is greatly improved, and the coke oven can be operated stably for a long period of time.

[Brief description of the drawings]

FIG. 1 is a graph showing the pore distribution of silica brick obtained by the method of the present invention (product of the present invention) and untreated commercially available dense silica brick (commercial product) using a colloidal silica solution.

FIG. 2 is a graph showing a pore distribution when a zirconia sol solution is used.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-156257 (JP, A) JP-A-5-286756 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 41/80-41/91 C10B 1/00-57/02 F27D 1/00-1/18

Claims (3)

(57) [Claims] 1. A silicon impregnating liquid and / or a zirconium impregnating liquid having a viscosity at room temperature of 50 centipoise or less to which one or two kinds of chromium oxide and calcium carbonate having an average particle diameter of 0.01 to 1.0 μm are added, 2.5-1
A method for producing a brick for a coke oven, characterized in that the brick is impregnated under an atmospheric pressure of 00 mm of mercury. 2. The method according to claim 1, wherein said brick has an average particle size of 0.01 to 1.0 μm under an atmospheric pressure of 2.5 to 100 mm of mercury.
A brick for a coke oven characterized by being impregnated with a silicon impregnating liquid and / or a zirconium impregnating liquid having a viscosity at room temperature of 50 centipoise or less to which one or two kinds of chromium oxide and calcium carbonate are added. 3. A coke oven wall structure, characterized in that at least a part of the wall surface of the coking chamber is made of the brick for coke oven according to claim 2.