JPH11281263A - Installation method of light weight castable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an easy installation of a lined heat insulating layer on the surface of the existing refractory while obtaining a better adhesion of the lined heat insulating layer for a long time after the installation thereof. SOLUTION: In this installation method, calcined gypsum is used as bond with a bulk specific gravity of 0.5-1.2 and thermal conductivity of 0.1-0.4 W/(m.K) after drying and a light weight castable containing ceramic fibers is installed as lined heat insulating layer on the surface of the existing refractory of an industrial furnace. In this case, a plurality of reinforcing materials 2 made of steel with the weight thereof of 60 g or less are bonded on the surface of the existing refractory 1 through a heatproof mortar 3 containing sodium silicate or sodium phosphate at a required pitch and then, the light weight castable is installed at a thickness of 30-100 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a lightweight castable in which a lightweight castable is applied as a lining insulation layer on the surface of an existing refractory in an industrial furnace such as a heating furnace or a general heat treatment furnace.

[0002]

2. Description of the Related Art Conventionally, a method of constructing such a lightweight castable is such that a bulk specific gravity after drying is 0.5 to 1.2 and a thermal conductivity is 0.1 to 0.4 W / (m · K). A lightweight castable using gypsum as a bonding agent and containing ceramic fibers (Japanese Patent Application No. 8-146755 (Japanese Patent Application Laid-Open No. 9-30)
No. 1779)), since this lightweight castable is made of calcined gypsum as a binder, it has high adhesion and is lightweight, and its construction thickness is as thin as about 30 to 50 mm. It can be constructed directly on

[0003]

However, the conventional lightweight castable construction method uses plaster of gypsum as a bonding agent, so that it is rich in adhesion, and in the case of a heat insulating layer lining a wall or the like, it is sufficient for a long time. However, in the case of a heat insulating layer lining the ceiling, it is difficult to maintain the adhesiveness over a long period of time due to the load of its own weight and the like, and there is a problem that it will fall off after several months of use. Most of the surface of the existing refractory on the ceiling has been vitrified due to the reaction with the scale due to the operation of the furnace. Probably because of difficulties. In order to solve such a problem, an anchor stud such as a Y type or a V type made of stainless steel such as SUS410 or SUS27 is used as in the case of constructing a construction body using an irregular-shaped refractory (excluding the block construction method). Although it is conceivable, the anchor stud is usually fixed by welding to the furnace casing, and in order to attach it to an existing refractory having a glassy surface, a hole is formed in the existing refractory, and furthermore, an anchor is provided. Work such as fixing the stud with mortar or the like occurs, which is inconvenient in terms of efficiency and process. In addition, since the existing refractories have been used for a long period of time, most of the surfaces have irregularities, and in order to make the construction thickness of the lining heat insulating layer uniform, the drilling dimensions should be taken into account when installing the anchor studs. Or to prepare several lengths of anchor studs, which can be a very difficult task. Therefore, the present invention provides a method for constructing a lightweight castable that can easily apply a lining heat insulating layer made of a lightweight castable to the surface of an existing refractory and that can improve the adhesion of the lining insulating layer after the construction over a long period of time. The purpose is to provide.

[0004]

In order to solve the above-mentioned problems, a method for constructing a lightweight castable according to the present invention comprises the steps of: providing a dried bulk having a specific gravity of 0.5 to 1.2; and a thermal conductivity of 0.1 to 0.4 W /
In (m · K), when a castable gypsum is used as a bonding agent and a lightweight castable containing ceramic fibers is applied as a lining insulation layer on the surface of an existing refractory of an industrial furnace, a weight of 60 g or less is applied to the surface of the existing refractory. After bonding a plurality of reinforcing materials made of steel having a required arrangement pitch via a heat-resistant mortar containing sodium silicate or sodium phosphate, the lightweight castable is constructed with a thickness of 30 to 100 mm. I do. The heat resistant mortar is preferably made of alumina or mullite.

[0005] The lightweight castable is 5 to 50 wt%.
Calcined gypsum, 1-50 wt% alumina or alumina
In addition to siliceous ceramic fibers, a refractory raw material comprising at least one of alumina, alumina-silica and chamotte, a porous material comprising at least one of alumina hollow aggregate, chamotte, perlite, vermiculite and artificial lightweight aggregate It may contain a raw material or at least one of clay, bentonite and ultrafine silica powder as required.

[0006] When the reinforcing material is made of steel, the reinforcing material is oxidized on the surface of the existing refractory which has been vitrified, and reacts and adheres. Further, the lining heat insulating layer made of a lightweight castable and the reinforcing material contact portion are one in one. By the partial melting reaction, the lining heat-insulating layer is strongly reinforced over a long period of time. The reinforcing material is made of ordinary steel, stainless steel, or the like, and has a thickness of 30 to 10 which is shorter than its thickness so as to be buried in the lining thermal insulation layer.
Y-type, V-type, L-type, bolts having a length of about 0 mm
An anchor stud such as a nut type is used. If the weight of one reinforcing material exceeds 60 g, it becomes difficult to bond and fix the ceiling to the surface of the existing refractory with heat-resistant mortar. The preferred weight is 50 g or less. In the case of a separable bolt / nut type anchor stud, the weight of one reinforcing member is the weight of the nut. The arrangement pitch of the reinforcing members depends on the construction conditions and is not limited. However, in general, it is preferable that the reinforcing refractories on the walls are large and the refractories on the ceiling are fine.

The heat-resistant mortar is preferably one that can withstand a temperature of 1400 ° C. or more in consideration of the operating conditions of an industrial furnace. When using a heat-resistant mortar, it is preferable to leave the mortar for 3 to 12 hours in order to develop adhesive strength. If a lightweight castable is constructed immediately after bonding, the reinforcing material will peel off from the surface of the existing refractory due to the effect of moisture in the castable, or the reinforcing material will drop due to vibration or pressure during construction.

[0008] In the construction of a lightweight castable, spraying and troweling are performed depending on the relationship between the construction thickness and the construction site. However, if time problems can be solved, casting construction using a formwork can also be adopted. . Construction thickness of lightweight castable,
If it is less than 30 mm, the boundary temperature between the existing refractory and the lining heat insulating layer exceeds 1200 ° C., so that the steel reinforcing material is completely melted and loses its function, and also the peripheral lining heat insulating layer is significantly damaged. Results. On the other hand, if it exceeds 100 mm, the boundary temperature will be less than 600 ° C., the surface of the reinforcing material will not oxidize, the reinforcing material will not react and adhere to the surface of the existing refractory, and the reinforcing material will not contact the lining insulation layer. The melting reaction of the portion does not occur, which tends to result in the lack of the reinforcing function.

[0009]

Embodiments of the present invention will be described below with reference to specific examples and comparative examples. Examples 1 to 5 First, as shown in FIG. 1 (a), a SUS or SS reinforcing material (V-shaped) was applied to an existing refractory 1 on the ceiling of a heating furnace and an existing refractory on a wall (not shown). Anchor stud) 2
As shown in (b), the base was adhered while being pressed by human power through a heat-resistant mortar 3 containing sodium silicate or sodium phosphate applied to the base end. Heat resistant mortar 3
The most suitable was Hyper Random (product code C-989) manufactured by Showa Kobunshi Co., Ltd. The arrangement pitch of the reinforcing material 2 is 50 to 100 mm on the surface of the existing refractory on the ceiling,
The surface of the existing refractory on the wall was set to 150 to 250 mm. Next, calcined gypsum 5 having a bulk specific gravity of 0.5 to 1.2 and a thermal conductivity of 0.1 to 0.4 W / (m · K) after drying.
50% by weight of ceramic fiber, 5% by weight of ceramic fiber, 10% by weight of refractory raw material and 50% by weight of kneading water at an external ratio of 40% to 120%.
wt%, and kneaded light castables were sprayed at the working thickness shown in Table 1 and each lining insulation layer 4
Was built. After a lapse of 6 months from the operation of the industrial furnace, a survey of the condition of each lining thermal insulation layer 4 was carried out. And was good. Therefore, the furnace body was cut at the position of the reinforcing material 2 in order to check the bonding state between the reinforcing material 2 and the existing refractory 1 and the lining heat insulating layer 4, etc., and as shown in FIG. It was found that the surface of the refractory 1 was oxidized with the reinforcing material 2 to be fixed by reaction, and that the contact portion between the lining heat insulating layer 4 and the reinforcing material 2 was partly melt-reacted to form a strong bond.

[0010]

[Table 1]

Comparative Examples 1 to 4 Comparative Example 1 does not use a reinforcing material as in the prior art, and Comparative Examples 2 to 4 use a reinforcing material similar to Examples 1 to 5 in which the ceiling and the wall of the heating furnace are installed. A heat-resistant mortar (Comparative Example 2,
3) After bonding using an epoxy resin (Comparative Example 4),
The same lightweight castables as in Examples 1 to 5 were sprayed on the ceiling of the heating furnace and the surfaces of the existing refractories on the walls at a construction thickness shown in Table 2 to construct respective lining insulation layers. After 6 months of operation of the industrial furnace, a survey of the condition of each lining insulation layer was conducted. In Comparative Example 1, although the lining insulation layer of the wall was well bonded, the entire amount of the lining insulation layer of the ceiling was dropped. Was. In Comparative Example 2, the reaction with the reinforcing material was large in both the ceiling and wall lining heat-insulating layers, and the blackening occurred, and melting of some of the lining heat-insulating layers was observed. In Comparative Example 3, although the condition of the heat insulating layer on the wall was good, surface peeling of about 30 mm of the surface layer was observed on the heat insulating layer on the ceiling. In Comparative Example 4, although the condition of the heat insulating layer of the wall was good, the heat insulating layer of the ceiling dropped off entirely,
No debris was observed.

[0012]

[Table 2]

Comparative Examples 5 to 7 In the same manner as in Examples 1 to 5, a reinforcing material was bonded to the surfaces of the existing refractories on the ceiling and the wall of the heating furnace using a heat-resistant mortar, and then the existing ceiling and walls of the heating furnace were installed. On the surface of the refractory, Comparative Example 5 is a lightweight castable B (bulk specific gravity 0.30, lightweight castable containing 1400 ° C ceramic fiber), and Comparative Example 6 is a lightweight castable (bulk specific gravity 1.25, lightweight castable containing ceramic fiber containing 1300 ° C). In Comparative Example 7, a refractory castable (bulk specific gravity: 2.00, 1400 ° C. refractory castable) was sprayed at a construction thickness shown in Table 3 to construct each lining insulation layer. After six months of operation of the industrial furnace, a survey of the condition of each lining insulation layer was conducted.
In Comparative Example 5, black spots due to the reaction with the reinforcing material were confirmed in both the ceiling and the wall heat-insulating layers from the viewpoint of being porous. In Comparative Example 6, although the condition of the heat insulating layer of the wall was good, the heat insulating layer of the ceiling dropped off entirely.
In addition, in Comparative Example 7, falling off was observed at the upper part of the heat insulating layer of the wall, and falling off of the entire surface of the heat insulating layer of the ceiling was observed.

[0014]

[Table 3]

In the above-described embodiment, the case where the V-shaped anchor stud is used as the reinforcing material has been described. However, the present invention is not limited to this. For example, as shown in FIG. As shown in FIG. 4, a reinforcing member 5 composed of a stud, a reinforcing member 6 composed of a bolt-nut type anchor stud provided with a nut portion 6a and a V-shaped stud portion 6b screwed to the nut portion 6a or an L-shaped anchor stud Reinforcing material (not shown) or a reinforcing material having another shape may be used.

[0016]

As described above, according to the method for constructing a lightweight castable according to the present invention, the reinforcing material is bonded to the surface of the existing refractory through the heat-resistant mortar, and the existing refractory is made vitrified. Reinforcement material is oxidized and fixed on the refractory surface, and the contact between the lining insulation layer made of lightweight castables and the reinforcement material is partially joined to cause a strong fusion. Can be easily applied, and the adhesion of the applied thermal insulation layer after the application can be improved over a long period of time.

[Brief description of the drawings]

FIGS. 1 (a), (b), (c), (d) are explanatory views of respective steps showing an example of an embodiment of a method for constructing a lightweight castable according to the present invention.

FIG. 2 is a sectional view of a lining heat insulating layer constructed by the construction method of FIG.

FIG. 3 is a front view of another reinforcing member used in the construction method of FIG. 1;

FIG. 4 is a front view of still another reinforcing member used in the construction method of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Existing refractory 2 Reinforcement material 3 Heat resistant mortar 4 Lining thermal insulation layer 5 Reinforcement material 6 Reinforcement material 6a Nut part 6b Stud part

Claims (2)

[Claims] 1. A lightweight castable having a bulk specific gravity of 0.5 to 1.2 after drying, a thermal conductivity of 0.1 to 0.4 W / (m · K), calcined gypsum as a bonding agent, and ceramic fibers. When installing as a lining insulation layer on the surface of an existing refractory of an industrial furnace, a plurality of steel reinforcing materials having a weight of 60 g or less are used on the surface of the existing refractory, containing sodium silicate or sodium phosphate. After bonding at a required arrangement pitch via mortar, the lightweight castable is
A method for constructing a lightweight castable, characterized in that the construction is performed with a thickness of 0 mm. 2. The method according to claim 1, wherein the heat-resistant mortar is made of alumina or mullite.