JPS63376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat storage brick with enhanced radiation efficiency. The heat storage chamber of a tank kiln for flat glass has the function of recovering heat from exhaust gas and transmitting the heat to the secondary air, and this heat storage chamber is generally constructed by stacking heat storage bricks in a lattice. The material of the heat storage brick used in such a heat storage chamber is selected depending on the purpose, as the brick itself should have a large heat storage capacity. Most of them only give various consideration to the way the bricks are laid, and no special consideration is given to improving the heat storage efficiency and heat exchange efficiency of the bricks themselves.

In contrast, the present inventors have found that radiation heat transfer has a large effect in the temperature range of this heat storage chamber, and that the effect is particularly remarkable in heat transfer to the bricks rather than the exhaust gas itself, which itself has radiant properties. We focused on the fact that even though secondary air itself does not have radiant power, it can be given radiant power by adding a portion of exhaust gas to it, thereby improving radiant heat transfer from the bricks to the secondary air. However, in this case, it was discovered that radiant heat transfer can be improved by increasing the apparent emissivity of the brick as a heat storage brick, and that if such a brick is used, the thermal efficiency as a heat storage chamber can be improved. be.

That is, the present invention has a large number of holes or grooves on the surface so that the surface opening or groove ratio is 25 to 75, and in the case where the surface has a large number of holes, the cross-sectional shape of the large number of holes is is circular or square, and the ratio L/R between the depth L of the hole and the short diameter R if the hole is circular or the minimum diameter R if the hole is square is 1 to
7.5, and if the groove is provided, the depth H of the groove is
and width W ratio H/W is 1 to 10, the material's original emissivity ε is 0.5 or more at 500℃ to 800℃, and the apparent emissivity ε is 0.8 or more at 500℃ to 800℃ 800 The gist is a heat storage chamber constructed with radiation enhancing bricks that has a radiation-enhancing temperature of 0.7 or more at temperatures between 1000°C and 800°C and 0.5 or higher at temperatures between 1000°C and 800°C.

The present invention will be explained below based on the heat storage bricks that constitute the heat storage chamber, but it is not necessary to construct the entire heat storage chamber with the heat storage bricks described below, and if necessary, a part or There is no problem even if most of the structure is made of other bricks, as long as these bricks are used in the main part that brings about the effect of the heat storage chamber of the present invention.

Furthermore, although the following explanation mainly refers to bricks with holes or grooves formed on one surface, it goes without saying that such holes or grooves may be formed on both surfaces or even on the side surfaces in some cases. or the holes or grooves may be penetrating.

First, the most basic aspect of the brick used in the present invention is one that has a large number of holes or grooves on its surface and has an emissivity εa that is at least a predetermined value at a predetermined temperature, which will be described later. It is.

In the present invention, the apparent emissivity εa refers to the emissivity increased by forming a large number of holes or grooves, compared to the emissivity ε of the brick material itself, which has no holes or grooves on its surface. Therefore, even if the emissivity ε of the material is originally higher than a predetermined value described below at a predetermined temperature, a heat storage brick that does not have many holes or grooves on its surface and whose emissivity is not enhanced in any way is considered to be a heat storage brick according to the present invention. It is not a target.

In addition, in this specification, emissivity ε and apparent emissivity εa both refer to values measured when the temperature of the brick is between 500 and 1500℃, but in reality, the temperature is outside this range. Of course, even when used, those having a predetermined emissivity enhancement effect within this range can similarly produce corresponding effects and are included in the present invention.

The idea of the present invention is that since it is necessary to have high radiation efficiency, the two points are that the apparent radiation rate εa is greater than or equal to a prescribed value at a prescribed temperature, and that radiation is enhanced. Therefore, in the case of materials whose emissivity ε is inherently large, increasing the emissivity by surface processing is effective even if it is relatively small, whereas for materials whose emissivity ε is originally small, There must be a large increase in emissivity above a certain level.

First, to specifically explain the apparent emissivity εa required for the heat storage brick of the present invention, εa is 500℃~
0.8 or more preferably 0.85 or more at 800℃, 800-1000
0.7 or more preferably 0.75 or more at 1000°C or more, and 0.5 or more preferably 0.6 or more at 1000°C or more, and these heat storage bricks have many holes or grooves on the surface to enhance the radiation effect. .

Here, the numerical values for the apparent emissivity εa were specified based on temperature in the case of heat storage bricks that are the subject of the present invention, that is, ordinary oxides such as MgO, Al ₂ O ₃ , Cr ₂ O ₃ , SiO ₂ , and ZrO ₂ This is because in the case of ceramics made of materials, the emissivity decreases as the temperature rises, and is usually less than 0.5 at temperatures above 1000°C, and at each temperature it shows the minimum value required for a radiant brick. In addition, nitrides such as Si ₃ N ₄ and
Carbides such as SiC do not have much of a drop in emissivity and usually fully satisfy this regulation, but they are more expensive than oxides and are susceptible to attack by alkalis, so they are limited to specific uses as radiation-enhancing heat storage bricks. Ru.

In the following explanation, for ease of understanding, both the material's original emissivity ε and apparent emissivity εa are determined when the temperature is 500.
Although we will show the value at ~800°C, this is because once the value at 500~800°C is determined, the value of ε will usually change in the same way in other ranges as well, roughly corresponding to the above-mentioned value. This is because it has been confirmed.

Next, the brick of the present invention must have a predetermined radiation enhancement effect, which is specifically achieved by forming specific holes or grooves on its surface, which will be described later. I will explain about it.

First of all, the emissivity enhancement effect usually has no meaning, no matter what material it is made of, unless the material's original emissivity ε increases by at least 0.03 due to surface processing. In the case of small items, it is necessary to make it larger by at least 0.1.

In other words, if the emissivity ε is originally 0.8 or more, the radiation effect as a brick is large even if there is no particularly large increase in ε, so the increase in the value of ε due to the process of forming holes or grooves should be at least 0.03. Cordierite (2MgO, 2Al ₂ O ₃ ,
There are materials such as 5SiO ₂ ), Si ₃ N ₄ , and SiC.

Also, the emissivity ε of the material is smaller than 0.8 and
For those larger than 0.5, improvement of emissivity by processing requires at least 0.1 or more, and preferably
The target materials include MgO, Al ₂ O ₃ ,
Some are mainly composed of oxides such as Cr ₂ O ₃ , SiO ₂ , and ZrO ₂ .

Next, the processing on the surface to bring about these radiation enhancement effects will be explained. The method is to form a large number of holes or grooves on the brick surface, and will be specifically explained below with reference to the drawings.

First, an example in which a large number of holes are formed on the surface will be described. FIG. 1 shows a typical example.

That is, the brick 1 of the present invention shown in FIG. 1 has a large number of cylindrical depressions 2 formed on its surface, and its cross-sectional shape is also circular.

Here, various shapes can be considered for the shape of this groove exhibiting a circular cross section.For example, one with the same diameter up to the bottom 3 as shown in Fig. 3, and one with a diameter that tapers toward the inner part as shown in Fig. 4. , or one in which the diameter is larger on the inside than on the surface, as shown in FIG. 5, may be used. Further, as shown in FIG. 6, the hole 2 may be a penetrating hole as long as it achieves the effects of the present invention. Further, the surface or cross-sectional shape of the hole does not have to be a perfect circle, but may be elliptical or partially angular.

Furthermore, although FIGS. 1 to 6 show examples in which the surface or cross-sectional shape is circular, the holes according to the present invention may of course have an angular shape.
A typical example is one in which the hole is square as shown in FIG. Even in the case of this angular shape, it goes without saying that various cross-sectional shapes are possible, as illustrated in FIGS. shape is possible. That is, the rectangular one shown in FIG. 8, the three shown in FIG.
Typical examples include a rectangular shape, a regular polygon such as a hexagon shown in FIG. 10, and a polygon having long and short sides as shown in FIG. 11.

Regarding the holes formed on such a surface, the specific diameter size, depth,
To explain their ratio and porosity, etc.
The diameter R (diameter or short axis when the shape is circular, the minimum diameter when the shape is square) is 3 to 70 mm, and the depth L is 3
~75 mm, the ratio L/R of these is 1 to 7.5, and the surface porosity is preferably 25 to 75%.

That is, if the diameter R is too small, it will take a lot of effort to process it, and it will also cause clogging during use and the effect will not be maintained.
This is because the thickness of the brick must be increased to increase the thickness of the brick, which reduces workability.On the other hand, if the brick is too large, the desired effect may not be obtained, and if the pore size is increased, the The more desirable range is 5.
~30mm. In addition, if the depth L is too shallow, the radiation efficiency may not improve sufficiently in relation to the diameter, and if the diameter is small, clogging may easily occur. This is because there is no difference in effectiveness and ease of processing decreases, so the more desirable range is 5 to 5.
It is 55mm. Also, if the ratio L/R of diameter R and depth L is too small, sufficient radiation efficiency may not be obtained. having no effect,
This is due to a decrease in processability, and a more desirable L/R value is 1.5 to 3.0.

In addition, if the surface porosity is too small, the effect of emissivity improvement by forming pores will not be sufficient, so if it is too large, it will be necessary to increase the pore diameter, which will increase the mechanical strength. In order to increase the number of holes, the diameter of the holes must be made very small, which requires a lot of processing time and is also prone to clogging, so the more desirable aperture ratio is 30~30. 60%
It is.

Note that the arrangement and distribution of the pores is of course preferably uniform when viewed from the surface, but is not necessarily limited to this and may be formed as appropriate within the range in which the effect can be obtained.

Next, an example of forming grooves on the surface will be explained. FIG. 12 shows a typical example.
When viewed from the surface, the grooves are formed so as to be perpendicular to the top and bottom, left and right, and the cross-sectional and longitudinal cross-sectional shapes of the grooves can be of various shapes as in the case of the holes described above.

Here, if the surface processing is a groove, the specific depth, width, hole area ratio, etc. will be explained.The width W is 2 to 65 mm, the depth H is 2 to 140 mm, and the depth to width ratio H/W is 1 to 10, and the groove opening ratio is preferably 25 to 75%.

In other words, if the width W is too narrow, it will clog during use and the effect will not last. On the other hand, if the width W is too wide and the opening ratio is increased, the mechanical strength will decrease, and if H/W is 1 or more, This is because the brick must be made thicker, which reduces workability, and the more desirable range is about 4 to 30 mm. In addition, if the depth L is too shallow, the radiation efficiency may not improve sufficiently in relation to the width, and if the width is small, clogging may easily occur.On the other hand, if the depth L is too shallow, there is no difference in effectiveness beyond a certain level. This is because ease of processing is reduced, mechanical strength is reduced, and workability is difficult, so it is usually desirable to have a thickness of about 5 to 50 mm.

Also, if the depth to width ratio H/W is too small, the groove will not have sufficient radiation efficiency, while if it is too large, it will not be as effective as when the depth H is too large, and the ease of processing will be reduced. This is because the bricks are less easy to install, and more preferably 1.5~
3.0.

In addition, the opening rate is 25 for the same reason as the opening rate.
~75% is desirable, and a more desirable range is 30-60%.

Various means of forming such grooves are possible, not limited to the example shown in FIG. Alternatively, it may be formed into curved grooves or folded grooves, may be formed with different intervals, or a combination thereof may be used.

Furthermore, in the present invention, holes and grooves can be used in combination, and the selection of these can be determined by considering the use, material, molding method, etc.

A heat storage room constructed using such bricks is
As a result of the implementation, in addition to the improvement in the apparent emissivity of the brick itself, it is thought that the area around the middle part of the brick itself, which has many recesses and grooves, effectively contributes to heat storage and heat transfer. It has been found that the heat exchange efficiency as a heat storage chamber has been improved, and it has great industrial value from the perspective of energy conservation.

[Brief explanation of the drawing]

FIG. 1 is a perspective explanatory view showing an example of a radiation-enhancing heat storage brick used in the present invention, FIGS. 2 to 6 are partially enlarged sectional views showing examples of various longitudinal cross-sectional shapes of holes, and FIG. The figure is a perspective partial explanatory view showing another example of the heat storage brick used in the present invention, FIGS. 8 to 11 are explanatory views illustrating some of the surface or cross-sectional shapes of holes, and FIG. 2A and 2B are perspective partial explanatory views showing other typical examples of formed heat storage bricks used in the present invention. In the drawing, 1 is a radiation-enhancing heat storage brick, 2 is a hole, and 4
indicates a groove.

Claims (1)

[Scope of Claims] 1. Having a large number of holes or grooves on the surface such that the surface opening or groove ratio is 25 to 75%, and in the case where the surface has a large number of holes, the large number of holes is The cross-sectional shape is circular or square, and the ratio L/R between the depth L of the hole and the short diameter R if the hole is circular or the minimum diameter R if the hole is square. 1~
7.5, and if the groove is provided, the depth H of the groove is
and width W ratio H/W is 1 to 10, the material's original emissivity ε is 0.5 or more at 500℃ to 800℃, and the apparent emissivity ε is 0.8 or more at 500℃ to 800℃ 800 A heat storage chamber constructed with radiation-enhancing bricks with a temperature of 0.7 or higher at temperatures between 1000°C and 800°C.