JPH03287025A - Method and device for measurement of temperature and emissivity of body and circumferential temperature - Google Patents

Abstract

PURPOSE:To know body temperature T, spectral emissivity epsilon, and the representative temperature Tw of a circumferential furnace wall by representing spectral radiation brightness signals as the sums of spectral radiation brightness signal components generated by a body to be measured and ambient stray light noise signal components, and using relational equations among spectral emissivity values. CONSTITUTION:The spectral radiation brightness signals L which different in one of the wavelength, polarization, and measured angle of heat radiation from the surface of the body in the furnace are shown by the equations I of Lx - LZ, where Lb is black body spectral radiation brightness and X, Y, and Z are indexes showing the wavelength, polarization, and measured angles. In each right side, a 1st term is a direct heat radiant component and a 2nd term is a stray light noise component from the circumferential furnace wall. When the surface of the body to be measured changes owing to oxidation, etc., spectral emissivity corresponding to the spectral radiation brightness signals varies, but when independent relation epsilony = fyx (epsilonx) and deltaz = fzy (epsilony) are already known, T, Tw, and epsilonx - epsilonz are found as their solutions. In this constitution, T, epsilon, and Tw can Tw can easily and accurately be measured even for the body which varies in emissivity epsilon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 2] The present invention is a method for accurately measuring the surface temperature of objects such as slabs that are conveyed stationary or at low speed in high-temperature heating furnaces such as slab heating furnaces in the steel industry. Radiation temperature measurement technology, which measures temperature without adversely affecting objects, can be applied not only to the steel industry but also to many other fields such as non-ferrous metals, ceramics, electronic materials, etc., where the temperature of objects in heating furnaces is measured.

[Conventional technology]

Taking a slab heating furnace as an example, the temperature control of the slab inside the heating furnace is carried out in the most consistent manner in the past. It was an estimate. With this method, it is difficult to accurately estimate the temperature of the slab, so there are problems in energy cost management, such as requiring a long baking time and setting a high temperature. On the other hand, it is possible to non-contactly measure the surface temperature of an object inside the heating furnace by radiation thermometry, but in this case, removing stray light noise from the inside wall of the heating furnace, etc. becomes a problem. As a radiation thermometry method that can deal with stray light noise, for example, the literature by Benuchi et al. (Benuchi, Ohno, Kusaka, "Development of a true temperature measurement system in a continuous annealing furnace", Tetsu-to-Hagane, Vol.
61, No. 8.11p2076-2C187)
There is a method using a water-cooled shielding plate, but when this method is applied to measuring the temperature of an object that is stationary or transported at low speed, such as a slab in a heating furnace, the water-cooled shielding plate cools the measured object. There was a problem in that this had a negative impact on quality.

In addition, as in JP-A-55-155218, a non-water-cooled shielding plate is used to remove unknown stray light noise from the reactor inner wall, and the effect of known stray light noise from the one-way valve water-cooled shielding plate is corrected to improve the surface of the slab. There is also a method of measuring temperature, but this method requires complicated calculations for correction, and the emissivity of the slab surface changes due to the generation of scale, and the contribution rate of stray light noise from the non-water-cooled drawing board increases. There were problems such as a risk of measurement errors occurring if the temperature changed.

[Problems to be Solved by the Invention 2] The purpose of the present invention is to reduce the influence of unknown stray light noise from the inner wall of the furnace by controlling the temperature of a measured object that is stationary or being transported at low speed in a high-temperature furnace such as a slab heating furnace. The object of the present invention is to propose a method and apparatus for simultaneously measuring the emissivity of an object.

[Means to solve the problem]

The method of measuring the temperature and emissivity of an object and the representative ambient temperature of the present invention detects three types of spectral radiance signals that differ from each other in wavelength, polarization, or measurement angle among thermal radiation from the object to be measured, Three equations that express each of these spectral radiance signals as the sum of the spectral radiance signal component emitted by the object to be measured and the stray light noise signal component from the surroundings, and the three spectral radiance signals corresponding to the spectral radiance signal. This method is characterized in that the temperature of the object to be measured, the three spectral emissivities, and the representative ambient temperature are determined by solving a total of five equations, including two independent equations expressing the relationship between the ratios.

Furthermore, the device for measuring temperature and emissivity of an object and representative ambient temperature of an object according to the present invention detects three types of spectral radiance signals that differ in wavelength, polarization, or measurement angle among thermal radiation from the object to be measured. means for calculating, from the three spectral radiance signals, three corresponding spectral emissivities and temperatures, and a calculation device that calculates the representative temperature around the object to be measured, the temperature of the object to be measured calculated by the calculation, and the three spectral radiance signals. It has a means for outputting emissivity and a representative temperature around the object to be measured, and means for inputting parameters for defining a functional relationship between the three spectral emissivities into the calculation device, and the calculation device outputs each spectral emissivity. The radiance signal is expressed as the sum of the spectral radiance signal component emitted by the object to be measured and the stray light noise signal component from the surroundings.
By solving a total of five equations: one equation and two independent equations expressing the relationship between the three spectral emissivities, the temperature of the object to be measured can be determined.
It is characterized by calculating three spectral emissivities, and L (ambient representative temperature).

:Production m: When detecting three types of spectral radiation B degree signals that differ from each other in wavelength, polarization, and measurement angle among thermal radiation from the surface of an object in the furnace, the deviation is calculated using the following formula % formula % (1) (2) (3) Where, T: Temperature of the object to be measured T,: Representative temperature of the surrounding furnace wall L: Spectral radiance Lb: Blackbody spectral radiance (known function of temperature T) ε: Spectral emissivity X・y・2: Subscripts representing differences in wavelength, polarization, and measurement angle The first term on the right side of equations (1) to (3) is the direct thermal radiation component from the object to be measured, and the second term is the direct thermal radiation component from the surrounding furnace. This is a stray light noise ring from the wall.

When the surface properties of the object to be measured change due to oxidation, etc., the three spectral emissivities corresponding to each spectral radiance signal also change, but an independent relational expression % (4 ) (5) is known, equations (1) to (5) can be solved numerically, and the five unknowns T, T, ε8ε9. ε2 can be found.

In this method, there is no need to use a water-cooled shielding plate or a non-water-cooled shielding plate, and there is no need to determine the representative temperature of the surrounding furnace wall in advance using a thermocouple or the like. Therefore, the configuration of the measuring device is simple, there is no need for special construction such as attaching a shielding plate to the furnace wall, and the temperature and spectroscopy of the object to be measured can be easily and accurately measured even for objects whose emissivity fluctuates. Emissivity,
Ambient representative temperature can be measured.

[Examples: Examples of the present invention will be described below with reference to the drawings. Figure 1 shows the configuration of the measuring device according to the present invention, where 1, 2.3 are radiometers for detecting three different spectral radiances, , Ly, and L, and 4 is an arithmetic processing unit. 5 is an input device such as a keyboard for inputting parameters, etc. for determining the functional relationships (4) and (5) to the arithmetic processing device 4; 6 is an input device such as a keyboard for inputting the temperature of the object to be measured and the spectral radiation obtained by the calculation; This is an output device for outputting the rate, representative ambient temperature, etc.

In order to select the wavelength in radiometers 1, 2, and 3, there is a method using, for example, an interference filter, and to select the polarization component, for example, a polarization beam splinter or the like can be used. If the measurement angles are different, the radiometers are installed at different direction angles, but if they only differ in wavelength or polarization, they can be housed in the same housing. Of course, depending on the wavelength band, for example, 5IG
It is possible to use photoelectric conversion elements such as e, PbS, etc. It goes without saying that spectral radiance can also be measured using an optical fiber as a waveguide.

FIG. 2 shows a measurement system for measuring the temperature of a slab in a heating furnace using the method of the present invention. In this example, since the slab temperature is determined by detecting spectral radiance signals with different wavelengths, measurement can be performed from the same direction, so there are three spectral radiance signals inside the radiometer detector 8.
A device for simultaneously detecting Ly and L is housed in an integrated manner.

9 is a slab heating furnace with a typical furnace wall temperature of TV, 10 is a slab with a surface temperature of T, and three emissivities of ε8. ε1.
ε2.

The respective spectral radiance signals are (1) and (2).

A direct radiation component 11 from the slab, which corresponds to the first term on the right side of equation (3), and a stray light noise component 12, which corresponds to the second term on the right side, are included. The three spectral radiance signals 7 from the radiometer detector 8 are transmitted to an arithmetic processing unit (not shown), and the slab temperature, three emissivities, and the furnace wall representative temperature are calculated and determined.

The relational expression between the spectral emissivities was obtained experimentally 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 functional representation (5) and a numerical table (5).
Wear.

[Effects of the invention: As described above, according to the present invention, even if the object is conveyed stationary or at low speed in a high-temperature furnace and the emissivity changes due to changes in surface properties, the object will not be affected by adverse effects such as cooling. Accurate temperature measurements can be taken without overheating. There are many applications where such temperature measurement is expected in the steel industry, such as slab heating furnaces, continuous annealing furnaces, and high brightness annealing furnaces, as well as other furnace interiors in the ferrous metal manufacturing industry, ceramic manufacturing industry, electronic material manufacturing industry, etc. If you also consider its application to temperature measurement, the effects on product quality improvement, operational management, energy savings, etc. are immeasurable.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of a measuring device according to the present invention, Fig. 2 is a diagram showing the configuration of a measuring device according to the present invention;
The figure shows a specific example of a measurement system for measuring the temperature of a slab in a heating furnace using the method of the present invention. The numbers in the figure are as follows. 1... Spectroradiometer, 2... Spectroradiometer, 3
... Spectroradiometer, 4... Arithmetic processing unit, 5
... Calculation parameter input device, 6... Output device, 7... Spectral radiance signal, 8... Radiometer detector, 9... Slab heating furnace, 10... Slab, 11...・Direct radiation component, 2nd... Stray light noise component.

Claims (1)

[Claims] 1. Detect three types of spectral radiance signals that differ from each other in wavelength, polarization, or measurement angle among thermal radiation from an object to be measured, and use each of these spectral radiance signals to be measured. Three equations expressed as the sum of the spectral radiance signal component emitted by the object and the stray light noise signal component from the surroundings, and two independent equations expressing the relationship between the three spectral emissivities corresponding to the spectral radiance signal. By solving a total of five equations, the temperature of the object to be measured, 3
A method for measuring the temperature and emissivity of an object, as well as the representative ambient temperature, characterized by determining the spectral emissivity and representative ambient temperature of an object. 2. Means for detecting three types of spectral radiance signals that differ from each other in wavelength, polarization, or measurement angle among thermal radiation from an object to be measured, and a means for detecting three types of spectral radiance signals that differ from each other in wavelength, polarization, or measurement angle, and detecting three corresponding spectral radiance signals from these three spectral radiance signals. a calculation device that calculates the spectral emissivity and temperature and the representative temperature around the object to be measured; a means for outputting the temperature of the object to be measured, the three spectral emissivities and the representative temperature around the object to be measured; The computing device has means for inputting parameters for defining a functional relationship between emissivities into the computing device, and the computing device calculates each spectral radiance signal from a spectral radiance signal component emitted by the object to be measured and from the surroundings. Three equations expressed as the sum of the stray light noise signal component and
The temperature of the object to be measured, the three spectral emissivities, and the representative surrounding temperature are calculated by solving a total of five equations, including two independent equations expressing the relationships between three spectral emissivities. Measuring device for temperature, emissivity, and representative ambient temperature.