JP6624019B2 - Construction method for irregular refractories - Google Patents

Description

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

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

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

Here, when an amorphous refractory is placed and heated around a cooling section in which cooling water (cooling medium) flows, such as a skid pipe of a heating furnace, the refractory also has a low thermal conductivity. Thus, the surface of the amorphous refractory is heated to a high temperature by heating, but the cooling portion (the inner peripheral side) is hardened at a relatively low temperature by heat absorption from the cooling portion.
In this way, the refractory that protects the cooling section is relatively hardened in a low temperature state and hardened in a high temperature state because it cures with a predetermined temperature gradient from the surface side to the cooling section side. It has different physical properties from that of the part. Generally, a refractory having a lower hardness is obtained when cured in a low temperature state than when cured in a high temperature state.

On the other hand, if it is attempted to apply the corresponding method by adjusting the physical properties by performing the above-described conventional component adjustment, for example, materials having different physical property values between the refractory on the cooling unit side and the refractory on the surface side are used. This can be dealt with by using them individually, but this is a very complicated construction.
The present invention has been made in view of the above points, and has as its object to improve the durability of a refractory applied around a cooling unit 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 around an outer periphery of a cooling unit arranged in a heating atmosphere to protect the cooling unit. A method for applying a fixed refractory, wherein a process of heating and curing an irregular shaped refractory provided on an outer periphery of the cooling unit is performed by stopping circulation of the cooling medium in the cooling unit. .

  According to one aspect of the present invention, when the amorphous refractory provided around the cooling part is hardened by a simple measure, 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 of an Example. It is a figure showing composition of a test piece used in an example. It is a figure showing an experimental result.

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

The method for constructing an amorphous refractory according to the present embodiment includes a pouring step, a curing step, and a heating step.
In the pouring step, a mold (not shown) is arranged around the target skid pipe 1 in a state where the temperature in the heating furnace is set to a temperature atmosphere such as 30 ° C. where the worker can enter, and the irregular shape is formed in the mold. Pour the refractory 2. As the amorphous refractory 2, refractories described in the prior art documents 1 and 2 may be used, 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 the refractory 2 has been cured for a period of time such as one day until the cast refractory 2 can maintain its shape.
FIG. 1 shows a state in which the curing step has been completed. Reference numeral 3 denotes a metal fitting provided on the skid pipe 1 for supporting the poured refractory 2.
In the heating step, the heating furnace is restarted, that is, a burner (not shown) of the heating furnace is operated to heat the inside of the heating furnace to a heating atmosphere. At this time, the supply of the cooling water to the skid pipe 1 (forcible circulation of the cooling water) is temporarily stopped. The suspension of the cooling water supply may be performed in advance, such as the timing of the pouring step. Here, when the supply of the cooling water is temporarily stopped, it is preferable that water is drained from the skid pipe 1 to be constructed.

The temperature around the refractory 2 gradually rises due to the heating in the heating furnace, and the refractory 2 is hardened by a dehydration reaction or the like due to the heating.
The inside of the heating furnace gradually rises to a high temperature state of, for example, 1200 ° C. by heating. 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 the present embodiment, based on the thickness and thermal conductivity of the refractory 2 that has been constructed, a known model formula or the like is used to determine whether the temperature of the refractory 2 on the skid pipe 1 side reaches the target heating temperature. The temperature is estimated in advance, and when it is determined that the temperature in the heating furnace has become equal to or higher than the set temperature in the heating furnace, the cooling water pump is driven again to restart the forced circulation of the cooling water to the skid pipe 1. Thus, the skid pipe 1 can be protected from thermal deterioration.

The target heating temperature is set in a temperature range higher than the curing start temperature of the amorphous refractory 2 and lower than the heat resistant temperature of the material constituting the skid pipe 1. Preferably, the temperature is set to 600 ° C. or higher.
Here, the strength of the refractory 2 applied differs depending on the temperature at the time of hardening, as in the example shown in FIG. 2, and the strength is relatively low (brittle) in a low temperature part.

For this reason, when heating is performed in a state where cooling water (for example, water at 30 ° C.) is forcibly circulated through the skid pipe 1, a low-strength refractory 2 in which the refractory portion of the skid pipe 1 is hardened at a low temperature is formed. Become. Therefore, the durability of the entire refractory deteriorates accordingly.
On the other hand, in the method for constructing the refractory 2 of the present embodiment, it is not necessary to perform complicated processing such as individually changing the component adjustment of the refractory 2 for each construction site, and the skid pipe 1 The refractory part 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, the high-strength refractory 2 having physical properties at high temperatures can be constructed by a simple method.

Next, examples according to the present invention will be described.
A construction experiment was performed using the irregular-shaped refractory 2 having the physical properties shown in FIG.
That is, a test piece shown in FIG. 3 was prepared and an off-line test was performed.
In this test, a refractory 2 having a thickness of 80 mm was poured into a surface 10a of a cooling section composed of a steel box section 10 capable of circulating cooling water 11 at 30 ° C., and then cured for one day. The prepared test pieces were prepared, and the surface, which was the heating surface 12A of each test piece, was heated to 600 ° C. In addition, the heat insulating material was stuck on the surface which contacts perpendicularly with the heating surface 12A, and the test was performed on the conditions which can obtain the heat insulating effect. Note that reference numeral 13 indicates the arrangement position of the temperature sensor.

FIG. 4 shows the results of the offline test.
The test was performed in two cases: a case where the cooling water was forcibly circulated through the cooling unit, and a case where the cooling water in the cooling unit was drained and the stop of the forced circulation of the cooling water was simulated.
FIG. 4 shows the measured temperatures 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 is higher under the heating condition in the uncooled state than in the heating condition in the state cooled by the cooling unit. Specifically, a temperature rise of about 50 ° C. was observed at a point 5 mm from the heating surface, and a temperature rise of about 80 ° C. was seen at a point 20 mm.
Thus, it can be seen that heating without performing forced cooling with cooling water can heat the entire refractory at a high temperature.

1 Skid pipe 2 Irregular refractories

Claims (2)

A method for constructing an irregular refractory in which an irregular refractory is provided on the outer periphery of a cooling unit disposed in a heating furnace with a forced circulation of a cooling medium to protect the cooling unit,
A method for heating an irregular refractory provided on an outer periphery of the cooling unit, wherein the treatment for heating and curing is performed by stopping circulation of the cooling medium in the cooling unit.   If it is determined that the temperature of the cooling unit surface is higher than the curing start temperature of the irregular refractory and lower than the heat resistant temperature of the material forming the cooling unit, the forced circulation of the stopped cooling medium is performed. The method of claim 1, wherein the refractory is restarted.

Images