JP3701451B2 - Infrared radiation burner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating body that radiates radiant heat when heated by a heating source and heats an object to be heated by the radiant heat. In particular, the present invention relates to a heating plate that radiates infrared rays when heated by a burner combustion flame to heat an object to be heated.
[0002]
[Prior art]
Conventionally, a heater that is heated by a heating source and heats an object to be heated by radiant heat from the surface thereof is known. Specifically, as shown in FIG. 4, an infrared radiation burner (hereinafter “burner”) in which a heating plate A is disposed below the burner body B is known. In the burner, fuel gas is supplied in a direction perpendicular to the drawing through the gas path C, and is further ejected through a flame opening D provided in the heating plate A, and ignited by an igniter (not shown) to form a combustion flame. The object to be heated E disposed below the heating plate A is heated and fired by the radiant heat radiated when the heating plate A is heated by the combustion flame.
[0003]
The radiant heat of the heating plate is expressed by multiplying the radiant energy of the black body expressed by Planck's formula by the emissivity of the heating plate. Therefore, the higher the emissivity of the heating plate, the greater the radiant heat radiated from the heating plate. The greater the radiant heat of the heating plate, the shorter the time required to heat and bake the object to be heated, the amount of gas supplied to the burner is reduced, and the energy efficiency is improved.
[0004]
Therefore, there is a demand for a heating plate having a high emissivity as compared with a heating plate made of cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ) or a stainless steel heating plate. Since the emissivity in a steady state of a heating plate made of cordierite, stainless steel, or the like is about 0.4 to 0.5, a heating having an emissivity of 0.60 or more, further 0.80 or more as a specific guideline. A board is desired.
[0005]
In addition, the emissivity generally depends on temperature, and there is a heating plate in which the emissivity decreases significantly as the temperature increases. For example, there is a heating plate whose emissivity at a low temperature is 0.60 or more, but the emissivity at a high temperature is reduced to about 0.3. When such a heating plate is used, it takes a long time to heat and bake the article to be heated, resulting in an increase in the amount of gas supplied to the burner and a decrease in energy efficiency.
[0006]
[Problems to be solved by the invention]
The present invention eliminates such inconvenience, and realizes a heating plate having an emissivity of 0.60 or more and further 0.80 or more on a regular basis without depending on temperature, and provides an energy efficient infrared radiation burner. For the purpose.
[0009]
[Means for Solving the Problems]
The burner of the present invention for solving the above problems is an infrared radiation burner that heats a heated plate by burning supplied fuel gas and heats an object to be heated by infrared rays emitted from the surface of the heated plate. The heating plate is provided with a coating layer made of La _1-x Sr _x MnO _{3 in} which _x is in the range of 0.00 to 0.90.
[0010]
_Hereinafter, a La _1-x Sr x MnO ₃ is abbreviated to LSM, the heating plate comprising a coating layer made of LSM abbreviated as LSM heating plate. An LSM hot plate in which x is in the range of 0.00 to 0.90 has an emissivity of 0.60 or more constantly without depending on temperature. That is, the LSM heating plate in which x is in the range of 0.00 to 0.90 has an emissivity of 0.60 or more from the start of heating by the burner combustion flame to the steady state. Therefore, by using the LSM heating plate, it is possible to realize a burner with high radiant heat and energy efficiency as compared with the case of using a cordierite heating plate or the like. Here, “emissivity” means spectral emissivity at a predetermined wavelength (hereinafter referred to as “specific wavelength”) near the peak position of the radiant energy of a black body at a predetermined temperature. The spectral emissivity at a specific wavelength is defined as the emissivity because the radiant heat of the heating plate is roughly determined by the spectral emissivity at the specific wavelength. This is because it may be considered to be substantially equivalent to the emissivity of Further, the “predetermined temperature” refers to an arbitrary temperature from when the heating plate is started to be heated by the combustion flame of the burner to a steady state where the temperature does not change with time.
[0011]
In order to further improve energy efficiency, the emissivity of the heating plate needs to be higher. As a specific measure, it is preferable to have an emissivity of 0.80 or more. The LSM heating plate in which x is in the range of 0.20 to 0.70 has an emissivity of 0.80 or more constantly without depending on the temperature. Therefore, by using such an LSM heating plate, it is possible to realize a burner with higher radiant heat and energy efficiency.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a partial cross-sectional view of an LSM heating plate, FIG. 2 is a relationship diagram showing the temperature dependence of emissivity, and FIG. 3 is a relationship diagram of x and the emissivity of the LSM heating plate.
[0013]
First, a method for manufacturing the LSM heating plate will be described. Mix the powder of La ₂ O ₃ , SrCO ₃ , Mn ₂ O ₃ , mixed with a stoichiometric amount of LSM, a pure water, and a dispersant so that the mixed water amount is 50%. The resulting product is pulverized for 12 hours using a wet ball mill. The pulverized raw material is sprayed on a heat-resistant base with a sprayer, the heat-resistant base is dried at 110 ° C. for 30 minutes, and then fired at 950 ° C. for 2 hours. In order to increase the thickness of the LSM coating layer on the heat-resistant substrate, the above-described spraying, drying, and firing operations may be repeated.
[0014]
In the present embodiment, a heat-resistant substrate having the heating plate A of FIG. 4 formed of cordierite is used, and x = 0, 0.2, 0.3, 0.4, 0.5, 0.7, and 1 are obtained. LSM of each composition was applied and baked. As the heat-resistant substrate, a stainless steel heating plate, a heating plate made of a heat-resistant alloy such as Hastelloy or Inconel, or the like may be used.
[0015]
FIG. 1 shows an enlarged cross-sectional view near the flame mouth D of the heating plate A at this time. The LSM heating plate 1 has a structure in which an LSM coating layer 3 covers the surface of a heat-resistant base 2 on which a burner combustion flame is formed.
[0016]
Next, the temperature dependence of the emissivity was examined for the LSM heating plates having the respective compositions manufactured by the above-described method. The measurement was performed at 407 [K], 673 [K], 873 [K], 1073 [K], 1123 [K]. Here, FIG. 2 shows the relationship between emissivity and temperature for only the LSM heating plate with x = 0.3. A solid line is a fitting line of each measurement point.
[0017]
The emissivity of the LSM hot plate with x = 0.3 is almost constant as the temperature rises. Although not shown here, the emissivity of LSM hot plates of other compositions is also almost constant as the temperature rises. The reason why the temperature dependence of the emissivity of the LSM hot plate is almost the same even when the composition is different is that the crystal structure of the LSM is almost the same regardless of the composition. Further, the emissivity of the LSM heating plate of each composition is almost constant even when the temperature rises because there is almost no change in the crystal structure of LSM due to the temperature.
[0018]
As already described, the emissivity here means the spectral emissivity at a specific wavelength at a predetermined temperature. In the temperature range of about 400 to 1100 [K] where the emissivity of the heating plate is measured, the peak position of the radiant energy of the black body is in the wavelength region of about 2.6 to 7.2 [μm]. Accordingly, 4 [μm] was selected as the specific wavelength common over the temperature range.
[0019]
Subsequently, the relationship between x and the emissivity of the LSM heating plate is shown in FIG. The points are the measurement points of emissivity at 407 [K] of the LSM heating plate of each composition, the actual curve is the fitting line of each measurement point, and the two dotted lines are values 0 that serve as a measure of emissivity in order from the bottom. .60 and 0.80, and the vertical solid line is a reference line indicating values of x = 0.2, 0.7, and 0.9 in order from the left.
[0020]
From the results of FIGS. 2 and 3, the LSM heating plate in which the value of x is in the range of 0.00 to 0.90 has a constant emissivity of 0.60 or more without depending on the temperature. I understand. Moreover, the LSM heating plate in which the value of x is in the range of 0.20 to 0.70 constantly has an emissivity of 0.80 or more without depending on the temperature. Therefore, with such an LSM heating plate, radiant heat sufficient to heat and bake an object to be heated more quickly than before can be steadily obtained without depending on temperature, and an energy efficient burner can be realized.
[0021]
Mix La powder other than La ₂ O ₃ , Sr compound other than SrCO ₃ , and Mn compound powder other than Mn ₂ O _{3 so} that La, Sr, and Mn have a ratio of 1-x, x, and 1, respectively. The coating layer may be fired. In this case as well, the composition of the coating layer is La _1-x Sr _x MnO ₃ , and by making the value of x in the range of 0.00-0.90, radiation is constantly 0.60 or more without depending on the temperature. A heating plate having a rate is obtained. Further, by setting the value of x in the range of 0.20 to 0.70, a heating plate having a constant emissivity of 0.80 or more can be obtained without depending on the temperature.
[0022]
A powder of a heat-resistant base made of cordierite or the like is further mixed with the powder of the fired La compound, Sr compound and Mn compound mixed so that La, Sr and Mn are in the ratio of 1-x, x and 1 respectively. Alternatively, the heated plate may be produced by molding and firing the kneaded raw material. Such a heating plate also has substantially the same emissivity as an LSM heating plate obtained by applying and firing powders of La compound, Sr compound and Mn compound on a heat-resistant substrate.
[0023]
La, Sr, and Mn compound powders are mixed and fired so that La, Sr, and Mn have a ratio of x, y, and 1, respectively (where x + y ≠ 1, x ≠ 0), and La _x Sr _y MnO. A coating layer having a composition of _z may be formed. The heating plate provided with such a coating layer also has an emissivity of 0.60 or more constantly without depending on temperature, and an energy efficient burner can be realized by using the heating plate.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of an LSM heating plate. FIG. 2 is a relationship diagram showing the temperature dependence of emissivity. FIG. 3 is a relationship diagram of x and the emissivity of an LSM heating plate. Sectional view [Explanation of symbols]
1. Heating plate, 3. Coating layer

Claims (2)

An infrared radiation burner that burns supplied fuel gas to heat a heating plate and heats an object to be heated by infrared rays emitted from the surface of the heating plate,
The heating plate, infrared radiation burners, characterized in that it comprises a coating layer which x is from _{La 1-x} Sr x MnO ₃ in the range of 0.00 to 0.90. The coating layer, infrared radiation burner as claimed in claim 1, wherein x is equal to or consisting of _{La 1-x} Sr x MnO ₃ in the range of 0.20 to 0.70.

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