JP2007271161A - Furnace wall structure for heating furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a furnace wall structure capable of effectively suppressing heat loss from a furnace wall by a low facility cost. <P>SOLUTION: A shielding plate S is installed on an outer face side of a furnace outer shell of the heating furnace by providing a space from the furnace outer shell, or, in addition, one or more layers of shielding plates Sn are installed on an outer side of the shielding plate S by providing a space from the shielding plate. Heat loss from the furnace can be effectively suppressed, only a small facility cost is needed since it is a simple structure of just installing shielding plates on a furnace outer shell side, and particularly, it can be realized comparatively easily and inexpensively even in an existing heating furnace. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a furnace wall structure of a heating furnace used for heating, heat treatment, firing and the like of materials in technical fields such as metal industry and ceramic industry.

In the technical fields such as the metal industry and the ceramic industry, various heating furnaces for the purpose of heating, heat treatment and firing of materials are used. This kind of heating furnace is desired to have less heat loss from the furnace wall. However, in recent years, global warming has become a problem. reduction, the furnace can realize saving CO ₂ is desired.

Conventionally, refractory bricks, castables, plastic refractories, etc. have been used for the furnace walls of heating furnaces. Recently, ceramic fibers and alumina fibers with good heat insulation and low heat storage have been used as heat insulating materials. (For example, Patent Document 1).
On the other hand, as a furnace wall structure for the purpose of suppressing heat loss from the furnace wall, for example, Patent Document 2 is provided with an inner shell having a refractory lining on the inside and a space outside the inner shell. An outer shell and a heat insulating material filled in the space between the inner shell and the outer shell are provided, and the space between the inner shell and the outer shell can be decompressed.

Further, in Patent Document 3, a refractory material is thermally sprayed on a surface of a refractory heat insulating material by a water plasma apparatus to form a thermal spray coating layer, and the heat storage amount of the furnace wall and the amount of heat dissipated are reduced. Refractory insulation is shown.
Japanese Patent Laid-Open No. 2000-241081 Japanese Patent Publication No. 63-43673 JP 58-13986 A

However, the furnace wall structure of Patent Document 2 has a high equipment cost and is not particularly suitable for a large furnace. In addition, the fireproof heat insulating material disclosed in Patent Document 3 has a much higher thermal spraying capability than the gas plasma device, so that the water plasma device can be installed at a low cost, but the equipment cost is higher than the normal lining construction. Become.
Accordingly, an object of the present invention is to provide a furnace wall structure capable of solving the above-described problems of the prior art and effectively suppressing heat loss from the furnace wall with a small equipment cost.

The gist of the present invention for solving the above problems is as follows.
[1] A furnace wall structure of a heating furnace, wherein a shielding plate S is provided on the outer surface side of the furnace outer shell of the heating furnace with a space provided between the outer shell and the furnace shell.
[2] The furnace wall structure of the heating furnace according to [1], wherein a space between the shielding plate S and the outer shell of the furnace is closed by an end portion of the shielding plate S.
[3] In the furnace wall structure according to [1] or [2], the heating is characterized in that one or more shielding plates Sn are provided outside the shielding plate S and a space is provided between the shielding plates. Furnace wall structure.

[4] The furnace wall structure of the heating furnace according to [3], wherein a space between the shielding plates is closed by an end portion of the shielding plate on the outer layer side.
[5] The furnace wall of the heating furnace according to any one of [1] to [4], wherein the shielding plate S and / or Sn is made of a metal having a thermal emissivity of 0.3 or less. Construction.
[6] In the furnace wall structure according to any one of [1] to [5] above, a coating having a thermal emissivity of 0.3 or less is formed on the surface of the shielding plate S or / and Sn. Furnace wall structure.

According to the furnace wall structure of the present invention, heat loss from the furnace can be effectively suppressed, and energy saving and CO ₂ saving of the heating furnace can be achieved. In addition, since the structure is simple by simply installing a shielding plate on the outer surface side of the furnace outer shell, the equipment cost can be reduced. In particular, even an existing heating furnace can be realized relatively easily and inexpensively. it can.

FIG. 1 shows an embodiment of a furnace wall structure according to the present invention, wherein 1 is a furnace shell (iron skin), 2 is a heat insulating material disposed inside thereof, and 3 is a fireproof material further disposed inside thereof. A furnace wall X is constituted by the furnace shell 1, the heat insulating material 2, and the refractory heat insulating material 3.
On the outer surface side of the furnace outer shell 1, a shielding plate S is provided with a space 4 provided between the outer shell 1 and the outer shell 1 by being supported by a plurality of support members 5. The shielding plate S has substantially the same area as the furnace outer shell surface, and is installed so as to cover almost the entire furnace outer shell 1.

  Although the material of the said shielding board S is not specifically limited, It is preferable to comprise with the metal of the low thermal emissivity as small as possible. Since the heat transfer between the furnace shell 1 and the shield plate S is mainly due to heat radiation, the heat emissivity of the shield plate S should be lower in order to suppress the heat transfer between them. This is desirable. Therefore, the shielding plate S may be an iron plate (usually the thermal emissivity of the iron plate whose surface is oxidized is about 0.7), but a metal having a lower thermal emissivity, specifically, a thermal emissivity of 0.3 or less. It is preferable to be comprised with a metal. Examples of such metals include aluminum or aluminum alloy plates (normal thermal emissivity: about 0.1 to 0.2), stainless steel plates (normal thermal emissivity: about 0.2 to 0.3), and the like. Is mentioned. These metal plates are easy to handle during construction, and there is little risk of damage after installation.

In addition, a coating film having a low thermal emissivity can be formed on the surface of the shielding plate S. For example, even when an iron plate or the like is used for the shielding plate S, if such a coating film is formed, thermal radiation can be formed. It is possible to improve the heat insulation by suppressing the heat transfer due to. Specifically, a coating film having a thermal emissivity of 0.3 or less is preferable, and a commercially available thermal barrier paint (emissivity: 0.2 or less) or the like can be used as such a low thermal emissivity paint. .
In order to suppress heat transfer due to heat radiation between the furnace shell 1 and the shield plate S, the space 4 between the furnace shell 1 and the shield plate S has a thickness (external to the furnace) where heat convection hardly occurs. The distance between the shell 1 and the shielding plate S is preferably set, and therefore the thickness t ₁ of the space 4 is preferably 50 mm or less.

The plurality of support members 5 are arranged at appropriate intervals, and connect and support the shielding plate S to the furnace shell 1. The structure and material of the support member 5 are not particularly limited, and may be made of an appropriate metal material.
The heat transfer from the furnace shell 1 is due to heat radiation and heat transfer with the outside of the furnace periphery in the furnace wall structure without the shielding plate S, whereas in the furnace wall structure of the present invention as described above. Since the heat radiation from the outer surface of the furnace shell 1 and the shielding plate S is the main component, the heat insulation of the furnace wall can be improved and the heat flow rate from the furnace wall can be lowered.

  Two or more shielding plates can be provided. FIG. 2 shows an embodiment in which two layers of shielding plates are provided in the furnace wall structure of the present invention. Outside the shielding plate S as shown in FIG. A space 4a is provided and a second shielding plate Sn is installed. That is, on the outer surface side of the shielding plate S, the shielding plate Sn is provided with the space 4a provided between the shielding plate S by being supported by the plurality of support members 5a. The shielding plate Sn has substantially the same area as the furnace outer shell surface, and is installed so as to cover almost the entire furnace outer shell 1 together with the shielding plate S.

  Even when two or more shielding plates are provided in this way, the materials of the shielding plates S and Sn are not particularly limited, but as in the case of FIG. 1, a metal with low thermal emissivity as low as possible (preferably heat It is preferable to use a metal having an emissivity of 0.3 or less. Since the heat transfer between the furnace shell 1 and the shield plate S and between the shield plate S and the shield plate Sn is mainly due to thermal radiation, the shield plate is used to suppress the heat transfer between them. This is because the thermal emissivity of S and Sn is preferably low. Therefore, the materials of the shielding plates S and Sn are the same as those described in the embodiment of FIG. In particular, it is effective to form the shielding plate Sn on the outer layer side with a metal having a low thermal emissivity.

A coating film with low thermal emissivity (preferably a coating film with a thermal emissivity of 0.3 or less) may be formed on the surfaces of the shielding plates S and Sn. This coating film is the same as described in the embodiment of FIG. In particular, it is effective to form a coating film with low thermal emissivity for the shielding plate Sn on the outer layer side.
Further, in order to suppress heat transfer due to heat radiation between the shielding plate S and the shielding plate Sn, the space 4a between the shielding plate S and the shielding plate Sn has a thickness (shielding plate that is difficult to generate thermal convection). it is preferable to the distance) between the S and the shielding plate Sn, the thickness t ₂ of the order space 4a is preferably set to 50mm or less.

The plurality of support members 5a that support the shielding plate Sn are arranged at appropriate intervals, and connect and support the shielding plate Sn to the shielding plate S. The structure and material of the support member 5a are not particularly limited, and may be made of an appropriate metal material.
Although three or more shielding plates can be installed, if three or more shielding plates are installed, the effect of suppressing heat loss from the furnace increases, but the temperature of the furnace shell 1 (iron skin) increases. In some cases, the temperature becomes 300 ° C. or higher, which causes a problem in long-term use. From the viewpoint of durability of the furnace shell 1, it is generally desirable that the number of shield plates is two or less. .

In the furnace wall structure of the present invention, it is preferable that the space 4 between the shielding plate S and the furnace shell 1 is closed by the end of the shielding plate S. FIG. 3 shows an embodiment of such a structure, and an end portion of the shielding plate S is provided with a closing plate 6 that extends toward the furnace outer shell 1 and closes the space 4.
In this way, by making the space 4 between the shielding plate S and the furnace shell 1 closed by the end of the shielding plate S, the flow of gas in the space 4 is suppressed and generated by the flow of gas. Convective heat transfer from the surface of the furnace outer shell 1 can be suppressed, and the heat insulation effect due to the installation of the shielding plate S can be further enhanced.

Further, as shown in FIG. 2, when a space 4a is further provided outside the shielding plate S and one or more shielding plates Sn are installed, the space 4a between the shielding plates S and Sn is a shielding plate on the outer layer side. It is preferable that the structure is closed at the end of Sn.
For example, as shown in FIG. 2, when a single-layer shielding plate Sn is provided outside the shielding plate S, a closing plate that extends toward the shielding plate S and closes the space 4a is attached to the end of the shielding plate Sn. .

In this way, by adopting a structure in which the space 4a between the shielding plates S and Sn is closed by the end portion of the shielding plate Sn on the outer layer side, the flow of gas in the space 4a is suppressed as described in FIG. Convective heat transfer from the surface of the shielding plate S generated by the gas flow can be suppressed, and the heat insulation effect due to the installation of the shielding plate Sn can be further enhanced.
In the furnace wall structure of the present invention as described above, it is only necessary to install the shielding plates S and Sn on the outer surface side of the furnace shell 1, so that even an existing heating furnace can be installed relatively easily and inexpensively. be able to.

Next, in the furnace wall structure of the present invention, the results of examining the influence of the number and material of the shielding plates on the heat insulation effect and the furnace shell temperature are shown.
1 and 2 outside the furnace wall (furnace shell) in a heating furnace (furnace temperature 1250 ° C.) in which the furnace wall is composed of a refractory heat insulating material having a thickness of 300 mm and an iron skin (furnace shell) having a thickness of 15 mm. One or two or more shielding plates S and Sn having a structure according to the above are provided.

  FIG. 4 shows the relationship between the number of installed layers of the shielding plate and the heat insulating effect (heat loss ratio) when an iron plate (thermal emissivity 0.7) is used as the shielding plate. Heat flux from the furnace wall (heat loss rate from the furnace wall when the shielding plate is installed on the basis of heat flux from the furnace wall in the case (number of installed layers: 0) (heat amount per unit time and unit area) ). FIG. 5 shows the relationship between the number of shield plates installed and the surface temperature of the outer surface of the furnace shell (iron skin) when an iron plate (thermal emissivity 0.7) is also used as the shield plate. It is.

According to FIG. 4, the heat loss decreases as the number of installed layers of the shielding plate increases. On the other hand, according to FIG. 5, the furnace shell surface temperature, which was about 110 ° C. without the shielding plate, was about 190 ° C. when the number of shielding plates was one and about 190 ° C. when two layers were installed. Is about 240 ° C., and in the case of three or more layers, it is around 300 ° C. or 300 ° C. or more.
As described above, increasing the number of shield plates installed reduces heat loss, but if the shield plates are installed in multiple layers, the furnace shell surface temperature rises to 300 ° C or higher, so long-term furnace life is considered. Then it is not desirable. Therefore, it is preferable to determine the number of installation layers of the shielding plate from such a viewpoint.

  FIG. 6 shows the relationship between the number of installed layers of the shielding plate and the heat insulation effect (heat loss ratio) when an iron plate (thermal emissivity 0.7) and an aluminum plate (thermal emissivity 0.2) are used as the shielding plate. This is a comparison of the heat flux from the furnace wall without the shielding plate (number of installed layers: 0) (the amount of heat per unit time and unit area) when the shielding plate is installed. The heat flux from the furnace wall (heat loss ratio from the furnace wall) is shown. FIG. 7 also shows the number of shield plates installed and the outer shell of the furnace (iron skin) when an iron plate (thermal emissivity 0.7) and an aluminum plate (thermal emissivity 0.2) are used as the shield plates. The relationship with the surface temperature of the outer surface is shown in comparison.

According to FIG. 6, when an aluminum plate is used as the shielding plate, the rate of reduction in heat loss from the furnace wall is higher than in the case of an iron plate. However, as shown in FIG. 7, in the case of an aluminum plate, if two or more layers are installed, the furnace shell surface temperature is 300 ° C. or higher.
Therefore, it is preferable to use a metal plate with a low thermal emissivity such as an aluminum plate as the shielding plate, but the furnace shell surface temperature is more likely to rise than when using a metal plate with a high thermal emissivity. From such a viewpoint, it is preferable to determine the number of installation layers of the shielding plate.

In general, a shielding plate that uses a low thermal emissivity metal plate such as an aluminum plate, an aluminum alloy plate, a stainless steel plate, or a metal plate with a low thermal emissivity coating film is used. The heat insulation strengthening of the furnace wall can be achieved by setting the number of installed layers to 2 or less.
Further, the thickness t ₁ and 30 mm, fitted with a closing plate 6 closes the space 4 to the end portion of the shield plate S as shown in FIG. 3 the structure of the space (gap) between the shielding plate and the furnace shell Then, the heat insulating effect was further enhanced, and the heat flux passing through the furnace wall was about 95% of the heat flux passing through the furnace wall when the closing plate 6 was not provided.

The longitudinal cross-sectional view which shows one Embodiment of the furnace wall structure of this invention The longitudinal cross-sectional view which shows other embodiment of the furnace wall structure of this invention The longitudinal cross-sectional view which shows other embodiment of the furnace wall structure of this invention In the furnace wall structure of the present invention using an iron plate as a shielding plate, a graph showing the relationship between the number of installed shielding plates and the heat insulation effect In the furnace wall structure of the present invention using an iron plate as a shield plate, a graph showing the relationship between the number of installed shield plates and the furnace shell surface temperature In the furnace wall structure of the present invention using an iron plate and an aluminum plate as a shielding plate, a graph showing the relationship between the number of installed layers of the shielding plate and the heat insulation effect In the furnace wall structure of the present invention using an iron plate and an aluminum plate as a shielding plate, a graph showing the relationship between the number of installed layers of the shielding plate and the furnace shell surface temperature

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace shell 2 Heat insulating material 3 Refractory heat insulating material 4, 4a Space 5, 5a Support member 6 Closing plate S, Sn shielding plate X Furnace wall

Claims (6)

  A furnace wall structure of a heating furnace, characterized in that a shielding plate S is installed on the outer surface side of the furnace outer shell of the heating furnace with a space provided between the outer shell and the outer shell.   The furnace wall structure of a heating furnace according to claim 1, wherein a space between the shielding plate S and the furnace shell is closed by an end portion of the shielding plate S.   The furnace wall structure of a heating furnace according to claim 1 or 2, wherein a space between the shielding plates is further provided outside the shielding plate S, and one or more shielding plates Sn are installed.   The furnace wall structure of a heating furnace according to claim 3, wherein the space between the shielding plates is closed by an end portion of the shielding plate on the outer layer side.   The furnace wall structure of a heating furnace according to any one of claims 1 to 4, wherein the shielding plate S and / or Sn is made of a metal having a thermal emissivity of 0.3 or less.   The furnace wall structure for a heating furnace according to any one of claims 1 to 5, wherein a coating film having a thermal emissivity of 0.3 or less is formed on the surface of the shielding plate S or / and Sn.

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