JPH03287027A - Method and device for simultaneous measurement of temperature and emissivity of body - Google Patents

Abstract

PURPOSE:To realize the method and device for accurately measuring the temperature and effective spectral emissivity of the body to be measured which changes in surface state by continuous annealing, rolling, etc., at the same time by installing a reflection body opposite a measurement point on the surface of the body to be measured and increasing the effective spectral emissivity. CONSTITUTION:When the temperature of an alloyed fused galvanized steel plate as the body 6 to be measured is measured in an atmosphere, the semispherical reflection body 1 which has, for example, its internal surface plate with gold to have a high reflection factor is installed opposite the measurement point and a spectral radiometer 2 detect two kinds of spectral radiation brightness signals which differ in one of the wavelength, polarization, and measured angle of heat radiation from the measurement point through an opening part bored in part of the semispherical reflection body 1. Then two equations represented as the sums of the black spectral radiation brightness and effective spectral emissivity of the body 6 to be measured and an equation showing the relation between two effective spectral emissivity values, i.e. three equations are solved by an arithmetic processor 3. Consequently, the temperature of the body 6 to be measured and two effective spectral emissivity values can be found.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the surface temperature of a heated object to be measured whose surface state is unknown. According to the method according to the invention, the thermal radiation signal from the object to be measured is divided into two different wavelengths, polarization states,
Alternatively, the temperature of the object to be measured and the two effective spectral emissivities can be determined by measuring at different measurement angles and using a relational expression between the signal values and two predetermined effective spectral emissivities. I can do it.

[Conventional technology]

Conventional radiation thermometry requires that the emissivity of the object to be measured be known, but it is used in many industrial processes, especially steel manufacturing,
In metal industry processes such as aluminum and copper, and manufacturing processes for electrical and electronic materials, the spectral emissivity of the object to be measured is unknown, or the effects of phase transformation, alloying, oxidation, surface roughness changes, etc. in the process may be unknown. The spectral emissivity may change drastically. Therefore, it is often not possible to accurately measure temperature using conventional temperature measurement methods.

Attempts to effectively increase emissivity and measure temperature with high accuracy include, for example, the method of Drury et al. (M, D.

Drury, K.P., Perry, and T.L.
and M, A,, “Pyrometers for S
surface-temperature leather
ment, ” Journal of the Ir.
on and 5teel in5tituto, ~o
v., 19511pp, 245-250).

In this method, a hemispherical reflector is placed opposite the measurement point on the surface of the object to be measured, and the measurement accuracy is improved by increasing the effective spectral emissivity. However, with this method, it is not possible to increase the effective emissivity to 1, that is, to the extent that the measured object can be regarded as a black body, and it is not particularly applicable to objects whose emissivity is low and fluctuates. I can't.

[Problem to be solved by the invention]

The purpose of the present invention is to perform continuous annealing, alloying treatment, painting, baking,
The purpose of this paper is to propose a new radiation thermometry method that can accurately measure the temperature and effective spectral emissivity of objects whose surface conditions are changing during processes such as rolling and casting.

[Means to solve the problem]

The method of simultaneously measuring the temperature and emissivity of an object according to the present invention installs a reflector opposite the measurement point on the surface of the object to increase the effective spectral emissivity, and the thermal radiation from the surface of the object to be measured is increased. Of these, the wavelength, polarization, or measurement angle is different from each other.
Two equations that detect various types of spectral radiance signals and express each of the spectral radiance signals as the product of the blackbody spectral radiance and the effective spectral emissivity at the temperature of the measured object, and the spectral radiance This method is characterized in that the temperature of the object to be measured and the two effective spectral emissivities are determined by solving a total of three equations, including an equation expressing the relationship between the two effective spectral emissivities corresponding to the signals.

Furthermore, the device for simultaneously measuring the temperature and emissivity of an object according to the present invention includes:
A reflector is installed facing the measurement point on the surface of the object to be measured, and the wavelength, polarization,
means for detecting two types of spectral radiance signals having different measurement angles; an arithmetic device for calculating two corresponding effective spectral emissivities and temperatures from the two spectral radiance signals; means for outputting the determined temperature of the measured object and two effective spectral emissivities;
means for inputting parameters for defining a functional relationship between two effective spectral emissivities into the arithmetic device, the arithmetic device converting each spectral radiance signal into a blackbody spectral radiation at the temperature of the object to be measured. By solving a total of three equations: two equations expressed as the product of luminance and effective spectral emissivity, and an equation expressing the relationship between two effective spectral emissivities, the measured object temperature and two effective spectral emissivities can be calculated. This method is characterized by calculating spectral emissivity.

[Production m: A hemispherical reflector whose inner surface is plated with gold to make it highly reflective is placed opposite the measurement point on the surface of the object to be measured, and an opening is made in a part of the hemispherical reflector. When two types of spectral radiance signals are detected from the thermal radiation from the measurement point through the sensor, which differ from each other in wavelength, polarization, and deviation in measurement angle, they are expressed by the following equation.

L i = ε i ・L, i (T> (1) Ly
=ε,・L,A(T) (2) However, T
: Measured object temperature L : Spectral radiance L, : Blackbody spectral radiance (known function of temperature) ε : Effective spectral emissivity The light emitted from the object is reflected by the reflector and re-enters the surface of the object to be measured, and is reflected again by the surface of the object to be measured, so the effective emissivity of the object to be measured is It will be much better than if you didn't have it.

When the surface properties of the object to be measured change due to oxidation, etc., the two effective spectral emissivities corresponding to each spectral radiance signal also change, but if Equation 5 expressing these relationships is known, then ( Equations 1) to (3) can be solved numerically, and the three unknowns T, ε8.ε, can be determined.The function f may be determined in advance experimentally, for example.

This method can be used not only to measure objects in the atmosphere, such as alloyed hot-dip galvanized steel sheets, but also to measure objects inside the furnace, such as cold-rolled steel sheets running in a continuous annealing furnace. can do.

Moreover, even if the emissivity changes due to alloying reaction or oxidation reaction, the temperature of the object to be measured can be accurately measured.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a specific example of a measurement system for measuring the temperature of an alloyed hot-dip galvanized steel sheet in the atmosphere using the method of the present invention. 1 is a hemispherical reflector, 2 is a spectroradiometer for detecting two different spectral radiances, Ly, 3 is an arithmetic processing unit, and 4 is a parameter for expressing the functional relationship (3), etc. An input device such as a keyboard for inputting data to the arithmetic processing device 3; 5 an output device for outputting the temperature of the object to be measured and effective spectral emissivity obtained by the calculation; 6 a steel plate as the object to be measured. .

To select the wavelength, for example, there is a method using an interference filter, and to select the polarization component, for example, a polarizing beam splitter or the like can be used. When the measurement angles are different, each radiometer is installed at a different direction and angle, but when the wavelengths are only different, as in the specific example shown in Figure 1, the two radiometers are installed in the same housing 2. It can also be stored inside. Of course, depending on the wavelength band, for example 3
Photoelectric conversion elements such as i, Ge, and PbS can be used. It goes without saying that spectral radiance can also be measured using an optical fiber as a waveguide.

It is desirable that the solid angle of the reflector from the measurement point be as large as possible, but it is still effective even if it is not so large as to cover the entire solid angle.

FIG. 2 is an example in which the apparatus according to the present invention is applied to temperature measurement of a cold-rolled steel sheet conveyed through a continuous annealing furnace.

1 is a spherical reflector, 2 is a spectroradiometer for detecting two spectral radiances with different polarization states, 3 is an arithmetic processing unit, and 4 is a manual input of parameters, etc. for expressing functional relationships to the arithmetic processing unit 3. 5 is an output device for outputting the temperature of the object to be measured and effective spectral emissivity obtained by calculation; 6 is a steel plate as the object to be measured;
7 is an annealing furnace wall, 8 is a jig for attaching the reflector l to the opening of the furnace wall, 9 is a transmission window for guiding the spectral radiance signal to the spectroradiometer 2 installed outside the furnace, and 10 is a steel plate. A spectral radiance signal 11 is radiated from the surface to the spectroradiometer, and is a spectral radiance signal that travels between the steel plate surface and the reflector.

The signal component of the spectral radiance signal shown in 10 is emitted directly from the steel plate surface in the direction of the spectroradiometer 2, and the spectral radiance signal shown in 11 is reflected from the steel plate surface and is emitted to the spectroradiometer 2. Some spectral radiance components traveling in the two directions are included.

The relational expression between the spectral emissivities was experimentally determined in advance and described using a simple mathematical expression using a polynomial. of course,
Various methods can be used to solve equations, such as using another function expression or expression as a numerical table.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to accurately measure the temperature of an object whose emissivity varies due to changes in surface properties. Such temperature measurement is expected to be applied to many industries such as continuous galvanizing and alloying furnaces, continuous annealing furnaces, and high brightness annealing furnaces in the steel industry, as well as other ferrous metal manufacturing industries,
If application in the ceramic manufacturing industry, electronic material manufacturing industry, etc. is also considered, the effects of improving product quality, operational management, energy saving, etc. will be immeasurable.

[Brief explanation of drawings]

Figure 1 shows a specific example of a measurement system used to measure the temperature of an alloyed hot-dip galvanized steel sheet in the atmosphere using the method of the present invention. This is an example in which the device according to the present invention is applied to temperature measurement of a cold-rolled steel plate. The numbers in the figure are as follows. DESCRIPTION OF SYMBOLS 1...Reflector, 2...Spectroradiometer 3...Arithmetic processing device, 4...Arithmetic parameter input device, 5...Output device,
6... Object to be measured, 7... Annealing furnace wall,
8... Jig for attaching the reflector 1 to the reactor wall opening, 9... Transmission window, 10... Spectral radiance signal radiated from the steel plate surface to the spectroradiometer, 11... Steel plate A spectral radiance signal passing between a surface and a reflector.

Claims (1)

[Claims] 1. A reflector is installed opposite the measurement point on the surface of the object to be measured to increase the effective spectral emissivity, and the wavelength, polarization, and measurement of the thermal radiation from the surface of the object to be measured are Two types of spectral radiance signals having different angles are detected, and each of these spectral radiance signals is expressed as the product of the blackbody spectral radiance and the effective spectral emissivity at the temperature of the measured object2. The temperature of the object to be measured and the two effective spectral emissivities are determined by solving a total of three equations: one equation representing the relationship between the two effective spectral emissivities corresponding to the spectral radiance signal. A method for simultaneously measuring the temperature and emissivity of an object. 2. Two types of spectral radiance signals that differ in wavelength, polarization, or measurement angle from the reflector placed opposite the measurement point on the surface of the object to be measured and the thermal radiation from the surface of the object to be measured. a means for detecting, a calculation device that calculates two corresponding effective spectral emissivities and temperatures from the two spectral radiance signals, and a temperature of the object to be measured and two effective spectral emissivities calculated by the calculations. a means of outputting,
means for inputting into the computing device parameters for defining a functional relationship between two effective spectral emissivities; By solving a total of three equations: two equations expressed as the product of radiance and effective spectral emissivity, and an equation expressing the relationship between two effective spectral emissivities, the measured object temperature and two effective spectral emissivities can be calculated. A device for simultaneously measuring the temperature and emissivity of an object, which is characterized by calculating the spectral emissivity of an object.