JPS6019444B2 - Method for measuring temperature of materials in heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of measuring materials such as steel materials being heated in a heating furnace using a radiation thermometer, and more specifically, the specifications of the shield member of the radiation thermometer and the measurement of side temperature. This paper proposes a temperature measurement method that enables highly accurate measurement by ensuring that the positional relationship between the object and the radiation thermometer satisfies predetermined conditions.

Previously, the temperature of steel in a heating furnace was controlled by controlling the furnace temperature, that is, controlling the side temperature, based on the idea that it was only necessary to heat the steel sufficiently. However, while attempts have recently been made to apply electronic computer control to heating furnaces,
Improve the quality of steel by not overheating it unnecessarily,
Moreover, as there is a trend to promote energy saving, it has become necessary to control the temperature of the steel material itself in the furnace. In order to measure the temperature of steel materials, a thermocouple contact type thermometer can be used for sample measurement, but a non-contact type thermometer must be used for actual products. Attempts have been made to measure fence temperature using a so-called radiation thermometer, which captures the infrared radiation emitted by an object and measures its surface temperature. However, there was a loss of steel in the furnace. Regarding temperature, there is a problem of the influence of furnace wall temperature. In other words, even if a radiation thermometer is placed to measure the surface temperature of the steel material, the infrared radiation energy emitted from the furnace wall, which is at a higher temperature than the steel material, is detected by the radiation thermometer's detection section (which detects the infrared radiation energy and determines the temperature). This is the part that converts the temperature into an electrical signal containing information, and generally uses an infrared detection element such as a Si cell), resulting in a measured value higher than the actual temperature. Furthermore, if the heating furnace is a walking beam furnace or a walking hearth furnace, the steel material is intermittently raised and lowered by the operator as it moves through the furnace.
The distance between the radiation thermometer placed above the steel material and the steel material differs when the steel material is in the raised position and when it is in the lowered position, and the influence of the furnace wall temperature is different in each case. Become. Furthermore, the furnace habit temperature varies depending on the operating conditions, and in short, it is not practical to use dimensions that require appropriate correction to the measured data to determine the surface temperature of the steel material. Therefore, in practice, a shield member is provided around the infrared radiation energy entrance of the radiation thermometer to suppress the energy entering from the furnace wall. The larger this shield member is, the more
Further, the closer the injection port and shield member are to the steel material, the less the influence of the furnace wall temperature can be reduced and the measurement accuracy can be improved, but there are physical practical limitations. The above-mentioned circumstances exist in the technology for measuring the temperature of steel materials in a heating furnace, so even though measurements have been made, it is unclear whether the measurement accuracy is at a certain level, and conversely, it is difficult to obtain the desired measurement accuracy. It was unclear what kind of measurements should be taken, and clarification was awaited.

The present invention has been made against this background, and the desired measurement accuracy is achieved by determining the specifications of the shield member and the distance between the nuclear shield member and the steel material that is the object of the side temperature to satisfy certain conditions. This paper proposes a method for measuring the temperature of the heating furnace.

The present invention will be specifically explained below based on the drawings.

FIG. 1 is a drawing showing the arrangement of the radiation thermometer, with reference numeral 1 indicating the ceiling portion of the furnace wall and reference numeral 2 indicating the steel material to be overflowed. The radiation thermometer consists of a detection section 3 disposed above the furnace wall 1, and a meter or data output section (not shown) arranged at an appropriate position and connected to the detection section 3.
is stored in. 5 is a cylindrical shield member made of caster pulls, 6 is a cylindrical cooling cylinder through which cooling water flows through the shield member 5, and both are covered with castables on the outer periphery and inner periphery of the lower end of the cooling cylinder 6. As shown, the shield member 5 is formed into an integral structure.

Then, insert the shield member 5 into the insertion hole la opened in the furnace wall 1 so that the shield member 5 is vertical,
The lower end of the shield member 5 is made to face the steel material 2. The infrared radiation energy emitted from the surface of the steel material 2 enters the cooling cylinder 6 from the lower end entrance of the shield member 5 and reaches the detection section 3, where it is converted into an electrical signal and the surface temperature of the steel material 2 is increased. However, since there is a distance of dimension d between the lower end surface of the shield member 6 and the steel material 2, there is a distance between the ceiling part of the furnace wall 1 or the side wall part (not shown) The emitted infrared radiation energy also directly or indirectly enters into the cooling cylinder 6 through the opening at the lower end of the shield member 5, causing measurement errors.

In the temperature measuring method according to the present invention, in order to measure the temperature of the heating furnace material such as the steel material 2 while satisfying the measurement accuracy a, the outer radius R of the shield part 5 and the nuclear shield part 5 are The relationship between the distance and the distance d of the steel material 2 is measured by satisfying the condition of formula 1' below.

True ≦ ・ -・--- (1) ['azu畔)n・keq2 However, n: Constant determined by the characteristics of the detection part of the radiation thermometer Ts: Temperature of the material (K) Tw: Furnace of the heating furnace Cooling temperature (K): Emissivity of material surface Next, the derivation process of equation 11 is shown.

Now, let us consider a case where a light amount of 1 is projected from the position of the detection section 3 toward the steel material 2 as shown in FIG. Since the reflection characteristics of the steel material 2 having oxides on the surface have relatively high diffusivity, if the shield member 5 is assumed to be a black body, the shield member 5
The following well-known formula '2} holds between the amount of light 1' diffused outwardly and the above 1. Child (・-go) (・-fujiminami) =
However, the emissivity K of the surface of the steel material 2; d/R, that is, the amount of projected light multiplied by 1 (day < 1) will be diffused outward.

Therefore, conversely, the radiation energy reaching the detection section 3 from the furnace wall 1 is multiplied by H due to the effect of the shield member 5. Now, if the measurement accuracy considering the error due to reflection from the furnace wall etc. is a, that is, when the amount of reflected light is measured at the ratio of the steel material temperature (absolute temperature), then the amount of reflected light from the furnace wall 1 and the amount of reflected light from the steel material 2 The relationship between the ratio G to the amount of emitted light from and the measurement accuracy a(a<<1) is given by the following equation {31.

G=nS+aTS)n・DoichigorSn≠an...
{3, TSn・However, Ts: Steel temperature (K) n: Constant determined by the characteristics of the detection part 3 If the furnace down temperature Tw (K) is △Tdeg higher than the steel temperature Ts (K), then the furnace wall 1 The amount of light 1'' reflected by the steel material 2 and incident on the detection unit 3 is given by the following formula [4} when the furnace core 1 is assumed to be a black body.

r=b. (Ts + △T) n × days ... [41 However, b: constant by thermometer Therefore, in order to satisfy measurement accuracy a, that is, to make the measurement accuracy less than a, from the relationship of equation {3', b・(TS+△TrXH MiG≠an “
- [51b, TSn, etc. are established.

The above equation {5} is rewritten as the following equation (2), and when this inequality is solved for k=d/R with Tw=Ts+ΔT, the above equation {11 is obtained. an (・ten belts) nX
÷X (1-Dosei 2.. Arrival) Therefore, the present invention has two meanings depending on the treatment of the steel material temperature Ts in the above-mentioned equation '1} and the above-mentioned derivation process.

That is, in order to satisfy the desired measurement accuracy a, the outer radius R of the shield member 5 and/or the shield member 5 and the steel material 2
In order to determine the separation dimension d from the steel material temperature Ts, it is necessary to treat the steel material temperature Ts as a value predicted from known data or operating conditions. Next, an example of measurement in a walking hearth furnace will be shown to prove the validity of the present invention.

Measurement example 1 Furnace wall temperature Tw: 950oo Predicted temperature of steel material Ts: 90
00○n:13 Go:.

・8, measurement accuracy a should be 1% or less (d/R should be 1.
027 (when the steel is in the raised position), or a is 1
．． The outer radius R of the shield member should be 9% or less.
and its mounting position was determined.

As a result, the measured value of the radiation thermometer was 916°C when the steel material was in the raised position, and 928°C when it was in the lowered position.

On the other hand, if the true temperature of the steel is 905°C, which is the value measured by attaching a thermocouple to the steel, the measurement accuracy is 0.93% and 1.
The result was 95%, confirming that the expected measurement accuracy was met, and the validity of the method of the present invention became clear.

Measurement method 2 Using the furnace wall temperature Tw, n, and d/R when the steel material is in the raised position and the lowered position, respectively, as the same values as in measurement example 1, the equation {1' or [6} is used. Replace the inequality sign with an equality sign, set the actual value of the steel material surface temperature measured by the thermocouple (850 pm C) as Ts, and calculate the values indicated by the radiation thermometer when the steel material is in the raised position and the lowered position, respectively. The temperature was determined to be 870oo and 887°C.

On the other hand, the actual values measured by the radiation thermometer were 8 degrees Celsius and 884 qo, respectively.
Thus, the validity of the method of the present invention has become clear from the fact that the calculated value and the actual value measured by the radiation thermometer are in good agreement. As described above, according to the present invention, it is possible to manage the measurement accuracy when measuring the side temperature of the steel material in the heating furnace, so it is possible to perform precise furnace temperature control based on the actual measured value of the steel material temperature. Therefore, the steel material is not overheated unnecessarily, energy saving can be promoted, and accuracy of steel material extraction temperature can be improved, and the present invention greatly contributes to reducing production costs and improving product quality.

[Brief explanation of drawings]

FIG. 1 is an elevational sectional view showing the positional relationship between the shield member and the steel material for explaining the method of the present invention, and FIG. 2 is a schematic diagram for explaining the formula [21]. 1...Furnace wall, 2...Steel material, 3...
...detection section, 5... ...Shield member. Multi-figure multi-figure 2

Claims (1)

[Claims] 1. In a method of measuring the temperature of a material being heated in a heating furnace using a radiation thermometer, the radiation thermometer is used to measure the temperature of the material while satisfying measurement accuracy a. The relationship between the outer circumferential radius R of the shield member provided in the part facing the temperature measurement object in order to suppress radiant energy that enters the detection part from outside the temperature measurement object and the separation dimension d of the shield member and the material is shown below ( 1) A method for measuring the temperature of a material in a heating furnace, characterized in that the temperature is measured while satisfying the conditions of the formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, n: Constant determined by the characteristics of the detection part of the radiation thermometer Ts: Predicted temperature of the material (°K) Tw: Furnace wall temperature (°K) ε: Material surface emissivity