JP2018080868A - Construction method of castable refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of refractories constructed around a cooling section by a simple method.SOLUTION: A construction method of a castable refractory 2 for providing a castable refractory for protecting a skid pipe 1, in which cooling water is forcibly circulated and arranged in a heated atmosphere, on the outer periphery of the skid pipe 1. The process of heating and curing the castable refractory 2 provided on the outer periphery of the skid pipe 1 is performed by stopping the circulation of the cooling water in the skid pipe 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for constructing an irregular refractory (castable refractory) for protecting a cooling part used in a heated atmosphere such as around a skid pipe of a heating furnace. The construction of the irregular refractory includes repair (partial construction) with a refractory.

  In the conventional construction of irregular refractories, as described in Patent Document 1 and Patent Document 2, in order to improve the physical properties of the constructed refractories and prevent cracking and peeling over a long period of time, the irregular shapes used for pouring are used. Refractory components (alumina cement, expanded aggregate, water reducing agent, etc.) are adjusted.

JP 2005-152908 A JP, 2006-52960, A

Here, when the amorphous refractory is placed around the cooling part where the cooling water (cooling medium) flows like a skid pipe of a heating furnace and heated, the refractory has low thermal conductivity. Thus, the surface side of the amorphous refractory becomes high temperature by heating, but the cooling part side (inner peripheral side) is cured in a relatively low temperature state by heat absorption from the cooling part.
Thus, the refractory that protects the cooling part is cured in a relatively low temperature state and in a high temperature state because it cures in a state having a predetermined temperature gradient from the surface side to the cooling part side. Different physical properties in the part. Generally, a refractory having a lower hardness is obtained when cured at a low temperature than when cured at a high temperature.

On the other hand, when trying to apply the corresponding method by adjusting the physical properties by adjusting the components as described above, for example, materials having different physical property values between the refractory on the cooling side and the refractory on the surface side are used. It can be handled by using it individually, but this is a very complicated construction.
This invention is made paying attention to the above points, and it aims at improving the durability of the refractory material constructed around the cooling part by a simple method.

  In order to solve the problem, according to one embodiment of the present invention, a cooling medium is forcibly circulated and an irregular refractory is provided on the outer periphery of a cooling unit disposed in a heating atmosphere to protect the cooling unit. A method for constructing a regular refractory, characterized in that the treatment for heating and curing the irregular refractory provided on the outer periphery of the cooling part is performed by stopping circulation of the cooling medium in the cooling part. .

  According to one aspect of the present invention, when the amorphous refractory provided around the cooling unit is cured by a simple response, the temperature gradient becomes smaller than before, so that the entire refractory applied is brought to a high temperature state. can do. As a result, in one embodiment of the present invention, it is possible to construct a refractory having physical properties when cured at a high temperature.

It is a schematic diagram which shows the refractory construction state around a skid pipe. It is a figure which shows the physical property of the refractory material of an Example. It is a figure which shows the structure of the test piece used in the Example. It is a figure which shows an experimental result.

Next, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, a case where the construction site where the irregular refractory is constructed is a steel skid pipe disposed in a heating furnace for heating a steel piece will be described as an example. In this case, the skid pipe constitutes a cooling unit, and cooling water as a cooling medium is forcibly circulated in the skid pipe.
The present invention is applied to an amorphous refractory that is disposed in a high-temperature heating atmosphere such as in a heating furnace such as 800 ° C. or more and that protects a cooling part in which a cooling medium such as cooling water or cooling gas is forcedly circulated If applicable.

The construction method of the irregular refractory of this embodiment has a pouring process, a curing process, and a heating process.
In the pouring process, a mold (not shown) is placed around the target skid pipe 1 in a state where the temperature in the heating furnace is 30 ° C., such as 30 ° C., and an irregular shape is formed in the mold. Pour refractory 2 in. The refractory 2 described in the prior art documents 1 and 2 may be used as the amorphous refractory 2, or an amorphous refractory usually used in a heating furnace or the like may be used.

In the curing process, the mold is removed after curing for a period of time such as one day until the poured refractory 2 is in a state where the shape can be maintained.
FIG. 1 shows a state where the curing process is completed. Reference numeral 3 is a fitting provided on the skid pipe 1 for supporting the poured refractory 2.
In the heating step, the heating furnace is restarted, that is, the heating furnace burner (not shown) is operated to heat the inside of the heating furnace to make a heating atmosphere. At this time, the supply of cooling water to the skid pipe 1 (forced circulation of cooling water) is temporarily stopped. The supply of cooling water may be temporarily stopped in advance, such as the timing of the pouring process. Here, when the supply of the cooling water is temporarily stopped, it is preferable to remove water from the skid pipe 1 to be constructed.

The temperature around the refractory 2 is gradually increased by heating in the heating furnace, and the refractory 2 is cured by a dehydration reaction or the like by heating.
The inside of the heating furnace gradually rises toward a high temperature state such as 1200 ° C. by heating, but in order to cause sufficient dehydration reaction to the constructed refractory 2, it is usually heated to 600 ° C. or higher. Is preferred. However, since the refractory 2 has a low thermal conductivity, the refractory portion on the skid pipe 1 side may be much lower than 600 ° C. even if the inside of the heating furnace reaches 600 ° C.

  For this reason, in this embodiment, based on the thickness and thermal conductivity of the constructed refractory 2, the inside of the heating furnace when the temperature of the refractory 2 on the skid pipe 1 side becomes the target heating temperature from a known model equation or the like. If the temperature is estimated in advance and it is determined that the temperature in the heating furnace is equal to or higher than the set temperature in the heating furnace, the cooling water pump is restarted to restart the forced circulation of the cooling water to the skid pipe 1. Thereby, the skid pipe 1 can be protected from thermal degradation.

The target heating temperature is set to a temperature range higher than the curing start temperature of the amorphous refractory 2 and not lower than the heat resistance temperature of the material constituting the skid pipe 1. Preferably, it is set to 600 ° C. or higher.
Here, the strength of the constructed refractory 2 varies depending on the temperature at the time of curing as in the example shown in FIG. 2, and the strength is relatively low (brittle) in the low temperature part.

For this reason, when the cooling pipe (for example, water at 30 ° C.) is forcibly circulated through the skid pipe 1, the refractory part on the side of the skid pipe 1 is cured at a low temperature, Become. Accordingly, the durability of the entire refractory is deteriorated accordingly.
On the other hand, in the construction method of the irregular refractory 2 according to the present embodiment, it is not necessary to perform complicated processing such as construction by separately changing the component adjustment of the refractory 2 for each construction place, and the skid pipe 1 The refractory portion on the side can also be cured at a high temperature, and the entire refractory applied can be cured at a high temperature. As a result, in the present embodiment, it is possible to construct a high-strength refractory 2 having physical properties at high temperatures by a simple method.

Next, examples according to the present invention will be described.
A construction experiment was conducted using the irregular refractory 2 having the physical properties shown in FIG.
That is, the test piece shown in FIG. 3 was created and an off-line test was performed.
This test is carried out for 1 day after pouring the refractory 2 into a surface 10a of a cooling part made of a steel box 10 capable of circulating 30 ° C. cooling water 11 as a test piece so as to have a thickness of 80 mm. The prepared test piece was prepared, and the surface which is the heating surface 12A of each test piece was heated to 600 ° C. In addition, the surface which contact | connects the heating surface 12A perpendicular | vertical was affixed with the heat insulating material, and it tested on the conditions from which the heat insulation effect is acquired. Note that reference numeral 13 indicates the position of the temperature sensor.

The result of the offline test is shown in FIG.
The test was carried out in two ways: forcibly circulating cooling water in the cooling part, and for simulating stoppage of forced cooling water by removing the cooling water in the cooling part.
FIG. 4 shows the temperature measured at 5 mm and 20 mm from the heating surface.
As can be seen from FIG. 4, it can be confirmed that the temperature of the refractory 2 as a whole rises under the heating condition in the uncooled state compared to the heating condition in the cooled state in the cooling section. Specifically, a temperature increase of about 50 ° C. was observed at a point 5 mm from the heating surface, and a temperature increase of about 80 ° C. was observed at a point 20 mm.
Thus, it turns out that the direction heated without performing forced cooling with cooling water can heat the whole refractory in a high temperature state.

1 Skid pipe 2 Indefinite refractory

Claims (2)

A method for constructing an amorphous refractory in which an amorphous refractory is provided to protect the cooling part on the outer periphery of the cooling part disposed in the heating atmosphere while the cooling medium is forced to circulate,
A method for constructing an amorphous refractory, characterized in that the process of heating and curing an irregular refractory provided on the outer periphery of the cooling part is performed by stopping circulation of the cooling medium in the cooling part.   If it is determined that the surface temperature of the cooling section is higher than the curing start temperature of the amorphous refractory and lower than the heat resistance temperature of the material constituting the cooling section, forced circulation of the stopped cooling medium is performed. It restarts, The construction method of the amorphous refractory according to claim 1 characterized by things.

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