JPS6135490B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation temperature measurement method and apparatus that are effective in measuring the temperature of a high-temperature moving object.

The present invention has already devised a radiation temperature measurement method using a blackbody furnace in place of the reflecting mirror 12 shown in FIG. Since this method uses specular reflection, it is excellent in eliminating backlight noise and is effective in measuring the temperature of objects inside the furnace. However, an ideal blackbody furnace would have a large shape;
It also has some troublesome problems, such as the need to heat and maintain it at a constant temperature. Therefore, the present invention aims to provide a radiation temperature measurement method using specular reflection, which can omit the blackbody furnace. Next, this will be explained in detail with reference to the drawings.

In Fig. 1, 10 is the temperature measured object, 12 is a reflector, 1
4 is a rotating sector, and 16 is a radiometer. Object 10
12 is a reflecting mirror, 14 is a rotating sector, and 16 is a radiometer. The object 10 is, for example, a heating strip running in a furnace. In this case, the reflector 12 and rotating sector 14 are placed outside the furnace and look into the object 10 through the window 18. The radiometer 16 may be placed either inside the furnace or outside the furnace. The reflecting mirror 12 and the radiometer 16 are arranged at the same angle θ on both sides of the normal line NO to the object surface, and the reflecting mirror 12 is a plane mirror and is connected to a straight line connecting the point O and the reflecting mirror as shown in the figure. perpendicular to For this reason, there are the following radiation paths. That is, the object 10 at temperature T emits almost all the radiation of εθ・E _b (T), assuming that the emissivity in the θ direction is εθ.
Of these, the radiation directed toward the radiometer 16 enters the radiometer as is, and the radiation directed toward the reflecting mirror 12 is reflected by the reflecting mirror, specularly reflected at point O, and emitted. Entering 16 in total. There is a rotating sector on the front side of the reflecting mirror 12, that is, on the object 10 side, and this rotating sector consists of a blade portion 14a whose surface is an absorbing surface and a space 14b between them, as shown in FIG. 2a. Since the blade portion 14a intersects the straight line 12-O, it absorbs the reflected line from the object 10 and also reflects the reflection mirror 1.
It also blocks radiation from 2. Furthermore, this reflecting mirror 1
2. Also, since the rotating sector 14 is kept sufficiently cold relative to the temperature of the object 10, the radiant energy emitted from it is negligible. When the sector 14 absorbs and blocks radiation, the only radiant energy that enters the radiometer 16 is that emitted by the object 10. In other words, there is a possibility that radiation from the reactor wall or the like is reflected by the object surface and enters the radiometer 16, but since the possible specular reflection path is blocked by the sector 14, such backlight noise is not radiated. It will never be 16 in total. This point is an advantage of the radiation temperature measurement method that uses specular reflection. Note that this specular reflection becomes stronger as the angle θ becomes larger. Since the radiant energy entering the radiometer 16 is as described above, the following formula holds true.

E ₁ =τ・εθ・E _b (T) …(1) E ₂ =τ・[εθ・E _b (T) +r _a・τ ²・εθ(1−εθ)(1−p)E
_b (T) ...(2) Here, E ₁ and E ₂ are the energy incident on the radiometer 16 with and without shielding with the sector 14, and τ is the radiation transmission through the window 18 provided in the furnace wall in this example. r _a is the effective reflectance of the reflecting mirror 12, and p is the diffuse reflection coefficient of the object surface. From (1) and (2), E ₂ /E ₁ =1+ _ra・τ ² (1−εθ)(1−p) ∴εθ=1−1/ _ra τ ² (1−p)(E ₂ /E _1-
1)...(3) ≡1-K(G-1)...(4) Also, from equation (1), E _b (T)=E ₁ /τ・εθ...(5) These (3) or 4 and ( 5) From the formula, the emissivity ε of the object
θ and temperature T are determined. In addition, in this temperature measurement, G=E ₂ /E ₁ was actually measured, and K=1/ _ra・τ ² (1-p
) is treated as a constant. r _a and τ can be maintained at constant values if maintenance management is sufficient. Since p is the diffuse reflection coefficient of the steel plate to be measured, it is troublesome to actually measure it each time, so a value determined by measurement in advance is used. Therefore, the condition for performing this temperature measurement method with few errors is that the actual value does not deviate greatly from the predicted value. If K is constant, εθ has a linear relationship as shown in FIG.

FIG. 4 shows an arithmetic unit 40 for calculating εθ and E _b (T). The output of the radiometer 16 is sampled by a sampling lock synchronized with the rotation of the sector 14 to obtain E ₁ and E ₂ , and the divider 22 calculates G=E ₂ /
Get E ₁ . Output constant 1 from the setting device 34,
A subtracter 24 generates G-1, a setter 34 outputs a constant K, and a multiplier 26 generates K(G-1). This is subtracted from the constant 1 by the subtracter 28 to obtain the emissivity εθ=1−K(G−1) of the object. Also, the transmittance τ is output from the setter 34, and the multiplier 30 outputs the transmittance τ.
Create εθ and input it to the divider 32 to obtain E _b
Obtain (T)=E ₁ /τ·εθ. Thereafter, the object temperature T is determined by the radiant energy temperature converter 36.

If the object 10 is a strip conveyed through a furnace, the surface of the object will move up and down from time to time, and will also be tilted, and in some cases specularly reflected radiation will not be input to the radiometer. For this purpose, it is effective to use a plane mirror as the reflecting mirror and to have a predetermined width.
To explain this regarding FIG. 5, the object 10 has an angle φ
When tilted, the radiation along the path between the object surface O, the reflector midpoint 12a, the object surface O, and the radiometer 16 deviates from the radiometer 16 as shown by the dotted line. In this case, the radiation emitted from the point 10a of the object 10 will instead enter the radiometer 16 along the path shown by the arrow. On the contrary, it is preferable to determine the width of the reflecting mirror 12 in this way. Specifically, the following a=・tan2φ...(6) b=2sin2/cos(θ-3)...(7) holds true for the length and angle shown, so the above a exists for the expected maximum value of φ. Dimension the reflector so that it can be used.
It is also effective to use a diffuse reflector as the reflector 12. FIG. 6 shows a case where a cavity type reflector is used. In this case, when the object 10 is tilted, the arrows 〓〓〓〓
There may be multiple reflections as shown by F ₁ and the effective reflectance r _a may change. Therefore, a plane mirror is preferable as a reflecting mirror in view of ease of manufacture. Also, if you use a concave mirror instead of a plane mirror,
When the object 10 is in the furnace, the light-gathering properties of the concave mirror make it possible to reduce the size of the furnace wall window 18 located on the optical axis connecting the concave mirror and the measurement point of the object.

The rotating sector 14 may be a rotating disk consisting of a radiation reflecting surface 14c and a radiation absorbing surface 14a, as shown in FIG. 2b. In this case, the reflective surface 14c also serves as the reflective mirror 12. A void (cavity) may be used in the absorption surface. There are also scanning type radiometers 16, but when using this scanning type radiometer, an absorption surface is placed adjacent to the reflecting mirror 12, and the radiometer interacts with these reflecting mirrors in its scanning. You may also look at the faces alternately. In this case, rotating sectors are not required.

As explained above, according to the present invention, it is possible to perform self-reference type specular reflection type radiation temperature measurement without using a blackbody furnace, which is extremely beneficial. Although this temperature measurement method is advantageous for measuring the temperature of objects inside the furnace, it is of course not limited to this method.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 a,
b is an explanatory diagram of the rotating sector, Fig. 3 is a graph showing the relationship between G and εθ, Fig. 4 is a block diagram of the arithmetic unit, and Figs. 5 and 6 are explanatory diagrams of the radiation path when the object is tilted. It is. In the drawing, 16 is a radiometer, 12 is a reflector, 10 is an object, 40 is an arithmetic unit, and 14 is a rotating sector. 〓〓〓〓

Claims (1)

[Claims] 1. A radiometer and a reflecting mirror are placed on an object, and radiation from the object directly enters the radiometer, and radiation from the object is reflected by the reflecting mirror, further reflected by the object surface, and emitted. The radiation energy input to the radiometer is measured when the radiation from the object is reflected by the reflector and when it is shielded, and the radiation energy of the object is determined from the measured value. A method for measuring the surface temperature of an object, characterized by determining the emissivity and further determining the temperature of the object. 2. A reflector and a radiometer installed so that the reflected radiation from the reflector is specularly reflected on the object surface and input to the radiometer, and a reflector and a radiometer installed on the object side of the reflector so that the reflected radiation is emitted from the object surface and input to the radiometer. a rotating sector having a part that blocks radiation input to the object and a part that allows the radiation to pass through and the radiation reflected by the reflector to pass back to the surface of the object; and an operation for calculating the emissivity and temperature of the object from the output of the radiometer. A device for measuring the surface temperature of an object, comprising: 3. The device for measuring the surface temperature of an object according to claim 2, wherein the reflecting mirror is a plane mirror.