JPH03247545A - Fire-resisting heat insulation material and fire-resisting heat insulating structure - Google Patents

Abstract

PURPOSE:To obtain the material of high fire-resistance and high heat insulation having high mechanical strength by casting ceramic foams of specified composition and specified void into a fire-resistant castable to carry out formation. CONSTITUTION:The ceramic foams 2 which consists of the single or the mixture of Al2O3, ZrO2, SiO2 and have 60-90% void are casted into the fire-resisting castable 3 to form into a fire-resisting heat-insulating material. By this method, the low mechanical strength, the defect of ceramic foam, is reinforced by the fire-resisting castable filled around the ceramic foams, and moreover, the high fire-resistance and the low thermal conductivity, the merits of ceramic foam, are kept as it is, so that the material excellent in fire resistance, heat insulation and mechanical strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention provides a fire-resistant insulation material and a fire-resistant insulation material that can impart heat insulation ability to the permanent layer of the refractory lining of various industrial kilns and at the same time increase structural strength. Regarding structure.

BACKGROUND OF THE INVENTION As a permanent layer of the refractory lining of various industrial kilns, fireproof insulating bricks are generally used as the lining of refractory bricks in kilns of 1200° C. or higher. This prevents energy loss due to heat radiation from the kiln.

In recent years, the use of monolithic refractories as refractory materials has expanded, and various heat-insulating castables have been developed.

These fireproof insulation materials have numerous natural or artificial pores inside and generally have a small bulk specific gravity. As a result, the thermal conductivity is low and the compressive strength is low, so careful consideration must be taken to avoid excessive unbalanced loads, such as avoiding areas where special loads are applied or adding cushioning material to prevent expansion. Construction work has been forced.

In addition, since most fireproof insulation materials use porous insulation type aggregates, their melting points are low, with some exceptions, and their normal operating temperatures are typically 1400° C. or lower.

On the other hand, in recent industrial furnaces, particularly in the refractory linings used in steel processes, progress has been made in improving the refractories, resulting in significantly improved corrosion resistance and greatly contributing to extending the life of the furnace. for example,
Examples include the use of Al2O-15iC-C bricks in pig iron mixers, the use of Mg0-C bricks in converters, and the use of Al*O--MgO type monolithic refractories in ladles.

However, all of these refractories have high thermal conductivity, and the heat dissipation from the furnace body is greater than that of conventionally used refractories, leading to various operational problems.

In such a refractory lining, it is necessary to ensure heat insulation with the current lining structure, but the above-mentioned fireproof and heat insulating materials are not fully satisfactory. Another possible method is to make the permanent layer thicker than it currently is, but this method would reduce the volume of the furnace and conversely increase heat storage loss, so it cannot be a drastic measure. In particular, if the permanent layer is made of a refractory material that mainly uses heat insulation, it will not only lack structural stability, but also be used as a safety lining in the event of problems such as steel leakage. However, there is a need for fire-resistant insulation materials and fire-resistant insulation structures that have these properties.

In addition, reheating shrinkage rate is a property value that determines the usage conditions of fireproof insulation materials in relation to fire resistance, and this is the rate at which conventional fireproof insulation materials shrink when heated above a certain temperature. It indicates the service life limit, and as the material of the refractory lining changes, a material with a high service temperature, that is, a material with excellent fire resistance is required.

The low thermal conductivity material that is often used as a cushioning material is a wool-like inorganic fiber aggregate that is highly flexible or shrinkable under pressure. It turns into powder due to shrinkage and deterioration, making it unusable due to its volumetric stability.

As a countermeasure to this problem, fire-resistant flexible and pressure-resistant materials that exhibit flexibility after drying are produced by adding inorganic and/or organic fibers, synthetic resin emulsions, and/or rubber latex as resin components to fire-resistant raw materials at a predetermined ratio. A composite fire-resistant heat insulating material (Japanese Patent Publication No. 59-48779) consisting of a compressible fire-resistant flexible board and an inorganic fiber aggregate has also been proposed.

However, although the composite fire-resistant heat insulating material disclosed in Japanese Patent Publication No. 59-48779 has heat insulating properties in the thickness direction, it is highly flexible, so thermal stress occurs in three axial directions during intense thermal cycles. , structural imbalance tends to occur,
cannot be applied.

Problems to be Solved by the Invention When reinforcing insulation with a permanent layer in an industrial kiln, especially in a ladle for molten steel, if the permanent layer of the insulating brick is made thicker, the furnace volume becomes smaller and heat storage loss increases. Therefore, metal adhesion is likely to occur, and energy consumption for preheating increases. In addition, it has low thermal conductivity (λ = 0.2 kcal/m,
hr, 'C)'s insulation material has low compressive strength, so it cannot sufficiently support the weight of the lining bricks, and its service temperature is low, making the lining structure unstable in terms of reheating shrinkage rate. It's easy. Furthermore, heat-insulating castables are difficult to raise in temperature due to the heat-insulating ability of the refractory aggregates they are mixed with, tend to dry insufficiently, and are at risk of steam explosion due to heat received after receiving the steel, making them unreliable in terms of safety.

The object of the present invention is to provide a heat insulating material and a heat insulating structure which have low thermal conductivity, high fire resistance and high strength and are suitable as a permanent fire insulating material for the industrial kiln, especially a ladle for molten steel. That is.

Ru.

Means for Solving the Problems The present inventors have developed various methods to strengthen the insulation of the bottom of the molten steel ladle, the so-called bed structure, which requires particularly high insulation promotion in industrial kilns, especially in the current steel process. At the study stage, a diesel engine exhaust filter made of ceramic foam (A I =Os 99%, bulk specific gravity 0.6) was selected.
0, porosity 80%, and compressive strength 35 kg/cm"), this ceramic foam and refractory castable were combined to create a board-shaped refractory material as shown in FIG.

That is, the ceramic foam has a thickness of 35 mm and a diameter of 1
Processed into a disc shape of 00mm, with a height of 40mm and a piece of 90mm.
A plurality of disc-shaped ceramic foams (2) are placed in a honeycomb shape in a 0 mm quadrilateral wooden frame (1).
After pouring 1.0375% castable (3) and curing, the frame was removed and dried at 300°C for 10 hours to obtain a honeycomb-shaped board. After heat-treating it at 800°C for 2 hours, it was processed into a diameter of 700 mm, the mechanical strength was measured, and the bottom part was placed in a ladle with a capacity of 2.5 L.

- It was lined as a thermal layer and the insulation properties were measured. For comparison, a comparison was made with a disc made only of the above-mentioned castable.

As a result, compared to a disc made only of castable material, a honeycomb-shaped disc made of ceramic foam and castable material has 3 to 5 times the compressive strength, and the temperature of molten steel in the ladle is 3 to 5 times higher on average.
The temperature of the iron skin at the bottom of the pot was 10°C lower. That is,
They discovered that it was possible to obtain a fire-resistant insulation material with low thermal conductivity, excellent mechanical strength, and high fire resistance, and completed this invention.

In other words, this invention is AI! 03, Zr0z, 5iO=
A fire-resistant heat insulating material made by casting a ceramic foam with a porosity of 60 to 90% consisting of one or a mixture of the above with fire-resistant castable.

In addition, a fireproof insulation block made of ceramic foam with a porosity of 60 to 90% made of Alxos, ZrOx, and 5iO- alone or in a mixture as a core and poured with fireproof castable is lined with a permanent layer. be.

The ceramic foam used in this invention is A
I, 0. , Zr0z, and 5ift, singly or as a mixture, and has a porosity of 65 to 90%. Porosity is 6
If it is less than 5%, the heat insulation properties will be poor, and if it exceeds 90%, the mechanical strength of the ceramic foam will decrease and it cannot be used as a permanent layer.

The size of the ceramic form is 50mmφ ~ 250m
mφ, preferably 100-200 mm≠. 50m
If it is less than mH, construction will be complicated and it will take a long time to dry the resulting heat resistant body. If it exceeds 250 mm≠, damage may occur due to unbalanced loads from other lining materials, which is not preferable. Also, the thickness is 25mm to 150m
m is preferred. This is because if the thickness is less than 25 mm, the absolute thickness of the produced fireproof insulation material is small and there is a risk of damage due to unbalanced structural loads, and if it exceeds 150 mm, it exceeds the thickness of the permanent layer.

The shape of the ceramic foam is a plate having a circular or elliptical curved surface. Polygonal shapes can cause cracks and damage due to increased temperature of the construction object and stress concentration in the heated state.

This kind of ceramic foam is made by foaming arbitrarily, solidifying it, and then shaping it into a flexible polyurethane foam that is impregnated with ceramic slurry, dried, and fired, and has a three-dimensional skeletal structure with continuous pores. .

The ceramics used are Al201, Z r Q
The raw material is fine powder of t, 5ift alone or as a mixture. For this reason, ceramic foam has the same melting point as the ceramic used, so it exhibits extremely high heat resistance.
Although it has a high heat shrinkage temperature, it is porous and has a low compressive strength of 100 kg/cm" or less.

On the other hand, as the monolithic refractory, high alumina or high magnesia castable having a refractory rating of 34 or higher is used depending on the lining refractory. The moisture content during construction of monolithic refractories varies depending on the particle size composition of the material used, but the consistency is 150 to 3.
Adjust to 50 and use.

If the consistency is less than 150, the fluidity is poor, the fixation of the ceramic foam is incomplete, and the mechanical strength is low. Also, consistency 3
If it exceeds 50, the castable itself is porous and fragile, and it takes time to cure and dry after pouring, resulting in poor workability.

Castable construction is done by pouring or troweling, depending on the fluidity of the material.

Direct construction is possible if the bottom of the kiln is smoothed in advance. For upright side walls, ceramic foam is placed inside a wooden or metal frame that has been pre-assembled into the desired shape, and then castable is cast and molded into the brick or block shape. Assemble by temporarily fixing with mortar. Thereafter, the refractory lining is lined, dried with a burner, and used for operation.

Furthermore, a waterproof organic film is applied to the surface of the ceramic foam to prevent penetration and intrusion of moisture and coarse and fine aggregate in the castable, which is partly in the form of a slurry at the time of pouring into the castable. As a specific measure, most of these intrusions can be avoided by covering the surface of the ceramic foam with vinyl tape or the like, and the heat resistance, which is the original objective, is hardly affected.

The area ratio of the ceramic foam to the plane of the honeycomb-shaped heat insulating material is adjusted to be 60 to 90%. If the area ratio of the ceramic foam to the plane of the honeycomb-shaped insulation material is less than 60%, the desired insulation properties cannot be obtained, and if it exceeds 90%, the thickness of the castable filling between adjacent ceramic foams will increase. is less than 5 mm, resulting in a decrease in structural mechanical strength. The thickness of the castable filling between adjacent ceramic forms is
A suitable length is 5 mm or more, preferably 7 to 10 mm.

Therefore, to reinforce the castable part, heat-resistant inorganic or organic fibers such as stainless steel or other metal wires, ceramic fibers, or carbon fibers are suitable, and those with a diameter of 1m+n or less work effectively. .

Function: The fire-resistant heat insulating material of this invention is made by casting ceramic foam with high fire resistance and low thermal conductivity using fire-resistant castable, so the low mechanical strength, which is a drawback of ceramic foam, is reinforced by the fire-resistant castable filled around it. Furthermore, the advantages of ceramic foam, such as high fire resistance and low thermal conductivity, are inherited as they are, providing a fire-resistant heat insulating material with excellent fire resistance and heat insulation properties.

Further, the fireproof insulation material of the present invention is used for a permanent layer,
The refractory insulation structure for industrial furnaces, which is lined with refractory material, uses a refractory insulation material with excellent fire resistance and insulation properties as a permanent layer, compared to the case of using conventional insulating bricks or insulating castables. However, high insulation efficiency can be achieved with a relatively thin layer.

Examples Example 1 A plurality of alumina ceramic foams each having a diameter of 50 amφ and a thickness of 65 mm were installed in a metal frame measuring 500 m + n in length, 500 mm in width, and 65 m + n in thickness, with the area ratios of the whole being changed, and alumina castables were installed. A honeycomb-shaped block was created by pouring.

The A I z03 content of the alumina castable used was 80%, and the diameter was 1 mm and the length was 20 mm.
3% of stainless steel wire was added and the consistency was adjusted to 250 before use. Pour castable, vibration molding,
After removing the metal frame and drying at 150℃ for 20 hours,
It was heat cured at 00°C for 5 hours.

For comparison, except for not installing ceramic foam,
A block was manufactured by the same operation as above.

The compressive strength and side strength of each manufactured block were measured using a 15007 on press.

The results are shown in FIG. 2 as a ratio, with the measurement result of a block consisting only of castables without ceramic foam installed as 1.

As shown in Fig. 2, the honeycomb block of the present invention has an area ratio of 40 to 9 in the total area of the ceramic foam.
In the case of 0%, both have strength greater than that of the comparative example.

Example 2 A permanent layer with a thickness of 80 mm was constructed using the honeycomb-shaped block of the present invention on a permanent layer of a molten steel ladle having a capacity of 70 tons using fired bricks of A I *O-78% as the refractory refractory bricks.

The honeycomb block used had a porosity of 85% and a bulk specific gravity of 0.85, and was made of ceramic foam (A 1 to z 90%, Zr0z 8%) with a diameter of 50 mm and 150 mm, and alumina mortar was applied to a thickness of 1 mm. After drying, the distance between each ceramic form is 7.
mm or more, castable with Al gos 65% adjusted to have a consistency in the range of 200 to 270 was poured while smoothing the surface, cured for 24 hours, and then dried with hot air at 200°C for 48 hours. .

The above AI! on the perm layer of the above honeycomb block! 0
- Lined with 78% fired bricks and others, returned to operation and received steel.

For comparison, the thickness was 80mm using the conventional pouring method.
For each ladle with a permanent layer of mm thick, the bottom steel skin temperature was measured in 35 channels of receiving steel from the new ladle state to the time of mass brick replacement, and the average value was determined. the result,
In contrast to the average receiving temperature of 1680°C, the average value of the bottom skin temperature of the comparison ladle was 325°C, whereas in the ladle with the permanent layer of honeycomb-shaped blocks of this invention, the average value of the bottom skin temperature was 325°C.
It was confirmed that the temperature was significantly lowered to 09°C, and the amount of heat dissipated was significantly reduced.

Example 3 As a permanent layer on the side wall of a molten steel ladle with a capacity of 250 tons,
The honeycomb block of this invention was constructed to a thickness of 65 mm.

The conventional permanent layer is made of waxite bricks with a fire resistance rating of 30 and a thickness of 65
mm was being constructed.

The honeycomb block used is 500mm long and 50mm wide.
MgO-based ceramic foams with a size of 0 mm and a thickness of 60 mm, a porosity of 83%, a bulk specific gravity of 0.92, and a diameter of 50 mm and 70 mm are arranged so that the area ratio of the ceramic foams to the whole is 85%, A l *O-80
% castable with diameter 1mm and length 20mm 5US
304 fiber was added at 3%, the consistency was adjusted to 250, and the rest was poured in the same manner as in Example 1.

To construct a honeycomb block, the steel shell is lined with high alumina mortar, the core is inserted, and spinel-based pouring material is filled, and after curing for 48 hours, the core is removed and heated at 300℃ for 48 hours. After drying and preheating at an ambient temperature of 1100°C, operation was resumed.

In addition, for comparison, 35 channels of steel receiving from the new ladle state to the first mass brick replacement were repeated for ladles whose permanent layer was made of the same conventional 30-degree refractory stone bricks.

The average killing time until casting was 120 seconds, and the temperature inside the pot was 1608°C for the ladle made with the honeycomb block of the present invention, and 1594°C for the conventional ladle. That is, since the temperature in the ladle could be raised by 14°C, after the mass brick was replaced, steel was received with the tapping temperature lowered by an average of 10°C in the ladle according to the present invention. As a result, the ladle constructed with the honeycomb-shaped block of the present invention has a service life of 12 times less than that of the conventional ladle.
We were able to extend the channel from 0ch to 138ch.

Effects of the invention Compared to conventional fire-resistant insulation materials, the fire-resistant insulation material of this invention has the following advantages:
It has high fire resistance and high heat insulation properties, as well as high mechanical strength, so it is suitable as a refractory lining for industrial furnaces, especially ladle for molten steel, and is especially suitable for construction of permanent layer of ladle. Since it is possible to lower the temperature of the receiving steel and cast without avoiding metal sticking, the service life of the ladle can be greatly extended.

[Brief explanation of drawings]

Figure 1 is a schematic explanatory diagram of the prototype honeycomb block;
) is a plan view, (b) is a sectional view taken along line A-A in figure (a), and figure 2 is a comparison of the relationship between the area ratio of ceramic foam in the entire honeycomb-shaped block, compressive strength, and side strength in Example 1. It is a graph showing the ratio of compressive strength and lateral strength of an example with each being 1. 1... Wooden frame, 2... Ceramic foam, 3... Castable, Applicant: Sumitomo Metal Industries, Ltd.

Claims (1)

[Scope of Claims] 1. A fire-resistant heat insulating material made by casting a ceramic foam with a porosity of 60 to 90% consisting of Al_2O_3, ZrO_2, and SiO_3 alone or in a mixture using a fire-resistant castable. 2 Consisting of Al_2O_3, ZrO_2, SiO_3 alone or in a mixture, porosity 60-90%, diameter 50-2
50mm ceramic foam arranged in a honeycomb shape,
A fireproof insulation material made by pouring fireproof castable. 3 A fire-resistant insulation block made of a ceramic foam with a porosity of 60 to 90% made of Al_2O_3, ZrO_2, and SiO_3 alone or in a mixture as a core, and constructed by pouring fire-resistant castable, and lining it as a permanent layer. structure.