JPS6226692B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of measuring the temperature of materials in a furnace with high precision using a radiation thermometer. Conventionally, when measuring the temperature of the materials inside the furnace using a radiation thermometer, when the radiant energy from the furnace wall is reflected by the materials inside the furnace and enters the radiation thermometer, the radiation thermometer shows the actual material inside the furnace. Since a temperature higher than the above temperature is indicated, a radiation shield is generally used to prevent radiant energy from the furnace wall from entering the radiation thermometer by inserting a water-cooled insulating shield tube from the furnace wall close to the materials inside the furnace. The temperature of the material inside the furnace is measured using the method. However, in this case, in order to prevent the radiant energy from the furnace wall from being reflected by the materials inside the furnace and entering the radiation thermometer, it is necessary to make the distance d between the tip of the shield cylinder and the materials inside the furnace smaller. , it is necessary to make the outer radius R of the tip of the shielding cylinder larger, but in that case,
The temperature of the materials in the furnace decreases in the part facing the shield tube due to the heat absorption effect due to water cooling of the shield tube, causing uneven heating of the materials in the furnace, and the longer the shield tube becomes, the more heat is lost in the furnace due to water cooling. increases, which hinders the promotion of energy conservation. On the other hand, the distance d between the tip of the shielding tube and the material in the furnace and the outer circumferential radius R of the tip of the shielding tube are set to such an extent that uneven heating does not occur.
If you set , the radiant energy from the furnace wall will be reflected by the materials inside the furnace and will be incident on the radiation thermometer, but as a method to further reduce the measurement error caused by radiant energy from materials other than the materials inside the furnace. , by experimentally determining the measurement error radiant energy that changes depending on the values of d and R, and subtracting this experimentally determined measurement error radiant energy from the actual measurement value, the temperature of the material in the furnace can be determined. I'm trying to find it more accurately. However, as a practical matter, the measurement error temperature varies depending on various conditions such as the position and temperature of the furnace and heating materials in addition to d and R, so the experimentally determined error radiant energy is actually It is difficult to accurately measure the material inside the furnace by subtracting it from the measured value. In addition, as another method, in addition to the radiant energy E (Ta) of the apparent furnace material temperature Ta including the error temperature, the radiant energy E (Tb) of the furnace wall is reflected by the furnace material and the furnace material temperature increases. The radiant energy △E (Tb′) incident on the measurement radiation thermometer is actually measured and this △E
There is also a method of calculating the radiant energy of only the materials inside the furnace by subtracting (Tb') from the above E(Ta), but in this case, the radiant energy from the furnace wall E
It is difficult to accurately determine (Tb), which causes measurement errors. As a result, it not only interferes with precise rolling control, which requires highly accurate control of the temperature of the material in the furnace, but also has drawbacks such as uneven product quality. The object of the present invention is to measure the temperature of the material in the furnace using a radiation thermometer using a shielding tube, when at least one of the distance d between the tip of the shielding tube and the material in the furnace and the outer radius R of the tip of the shielding tube differs. From the measured radiant energy difference, find the error radiant energy due to radiant energy other than the materials in the furnace that enters the radiation thermometer, and obtain the temperature of the materials in the furnace by subtracting the error radiant energy from the radiant energy detected by the radiation thermometer. The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional methods by providing a method for measuring the temperature of materials in a furnace using a radiation thermometer. Next, the configuration of an embodiment of the present invention will be explained with reference to FIG. On the furnace wall 3 of the furnace 2 that heats the material 1 to be heat treated, a probe 8, which is a water-cooled, heat-insulating shield tube, is mounted on a bracket, with a caster 7 placed around the outer periphery of a triple water-cooled steel pipe 6 that forms a cooling water inlet 4 and a cooling water outlet 5. The probe 8 is installed vertically so as to protrude directly above the furnace material 1 through the probe 9, and an air inlet 10 for air purging inside the probe 8 is formed at the upper end of the probe 8, and a radiation thermometer 11 is also installed. Radiant energy from the in-furnace material 1 is incident on the radiation thermometer 11 via the probe 8. Furnace material temperature measuring device 1 configured as described above
2, if the distance between the probe 8 tip and the furnace material 1 is d1, and the outer radius of the probe 8 tip is R1, then the radiation thermometer 11 receives the radiant energy E (Tw) from the furnace wall 3 at the temperature Tw. Furnace material 1 at temperature T
The radiant energy E(T1') of the apparent temperature T1' including the measurement error temperature including the amount reflected and incident on the surface, that is, E(T1') = ε・E(T) + (1-ε) ・β1・E(Tw)...(1) is incident (see Figure 2). Here, ε: Emissivity of the material surface E(T): Radiation energy from a black body at temperature T β: Reflection mixing rate

[Formula] Therefore, if d=d1 and R=R1, Next, the values of d and R in this in-furnace material temperature measuring device 12 are shown by the two-dot chain line in FIG. 1, d=d2,
When changing R=R2, the reflection mixing rate β
2 is At the same time, the radiant energy E(T2') of the apparent temperature T2' including the measurement error temperature incident on the radiation thermometer 11 in this state is E(T2') = ε・E(T) + (1- ε) ・β2・E(Tw) ...(2) becomes. However, E(T1')≠E(T2'). Therefore, the radiation thermometer 11
The measurement error radiant energy incident on the furnace wall 3 is obtained by expanding the following equation. △E(T') = E(T1') - E(T2')...(3) can be obtained from the radiation energy difference measured by the radiation thermometer 11, and this (3)
Substituting equations (1) and (2) into the equation, △E(T')=E(T1')-E(T2') =(1-ε)・E(Tw)・(β1-β2)= (1-ε)・E(Tw)・β1(1-β2/β1)...
... (4) By expanding the above equation (4), the radiant energy of the measurement error temperature in equation (1) can be determined by the following equation. As a result, the radiant energy of the furnace material 1 can be determined by the following equation by substituting the above equation (5) into equation (1). Note that the above d between the probe 8 and the furnace material 1
The following method is used to measure the apparent temperature (T1') (T2') of the furnace material 1 by changing at least one of R and R. (1) In FIG. 1, at least one of the probe 8 and the furnace material 1 is displaced in the direction in which they face each other. (2) As shown in Fig. 3, two probes 8A, 8B with different at least one of d and R are provided, and each probe 8A, 8B is provided with a radiation thermometer (radiation detection element) 11A, 11B for calculation. Measure using circuit 13 or the like. (3) As shown in Figure 4, the two probes 8A,
One radiation thermometer 11C is provided for each probe 8B, and the radiation thermometer 11C is switched by a switching mechanism 14 for each probe 8A, 8B, and each output is connected to an arithmetic circuit 1.
3 and measure. Next, the effects of the present invention will be explained. The present invention allows the radiation energy from the in-furnace material located at the front end of the shielding tube inserted into the furnace to pass through the shielding tube and enter the radiation detection element of the radiation thermometer attached to the outer end of the shielding tube. When measuring the temperature of the material in the furnace by changing at least one of the distance d between the tip of the shielding tube and the material in the furnace and the outer radius R of the tip of the shielding tube, the actual radiant energy that is subject to the error temperature can be measured. The difference in error radiant energy is determined, and the temperature of the material in the furnace is measured by subtracting the error radiant energy from the detected radiant energy detected by the radiation thermometer. As a result, the present invention has the advantage that the true temperature of the material in the furnace can be determined easily and with high accuracy. In particular, even if the conditions of the furnace and the materials inside the furnace whose temperature is being measured, such as the temperature of the furnace and the materials inside the furnace whose temperature is being measured, or the material or shape of the materials inside the furnace whose temperature is being measured, the temperature of the furnace that is being measured is always maintained in a state that is responsive to these changes. This has the effect that the true temperature of the material inside the hot furnace can be easily measured with high accuracy.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the structure of an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the situation of the radiant energy, and Figs. 3 and 4 are measurement methods by changing d and R. FIG. 1...Furnace interior material, 2...Furnace, 3...Furnace wall, 8,
8A, 8B...Probe, 11, 11A, 11
B, 11C... Radiation thermometer, 12... Furnace material temperature measuring device, 13... Arithmetic circuit.

Claims (1)

[Scope of Claims] 1. Radiation energy from the materials in the furnace at the forward position of the shielding cylinder inserted into the furnace is transmitted through the shielding cylinder to the radiation of the radiation thermometer attached to the outer end of the furnace of the shielding cylinder. When measuring the temperature of the material in the furnace by making it enter the detection element, the distance d between the tip of the shielding cylinder and the material in the furnace
From the difference in radiant energy measured when at least one of the outer radius R and the outer radius R of the tip of the shielding tube is changed, it is determined that the radiant energy that is reflected and incident on the in-furnace material other than the in-furnace material corresponding to the values of d and R is In the furnace using a radiation thermometer, the temperature of the materials in the furnace is determined by determining the error radiant energy that is the error temperature from the radiation thermometer, and subtracting the error radiant energy from the detected radiant energy of the radiation thermometer. How to measure the temperature of materials. 2. Claim 1 characterized in that the distance d between the tip of the shielding cylinder and the furnace material is changed by displacing at least one of the shielding cylinder and the furnace material in a direction in which they face each other. A method for measuring the temperature of materials in a furnace using a radiation thermometer as described in . 3. At least one of the distance d between the tip of the shielding tube and the reactor material and the outer radius R of the tip of the shielding tube is measured via a radiation detection element for detecting the temperature of the material in the reactor provided in each of the plurality of different shielding tubes. A method for measuring the temperature of a material in a furnace using a radiation thermometer according to claim 1, characterized in that an error radiant energy is determined from the radiant energy generated by the radiation thermometer.