JPS6361885A - Method of determining state of damage of high-temperature furnace refractory wall - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for accurately estimating and understanding the wear and tear condition of a fireproof wall lined in a high-temperature furnace from the outside. In the following explanation, a blast furnace will be used as a typical high-temperature furnace, but converters, electric furnaces, and ladles are also included.

The present invention can also be applied to a wide range of furnace bodies including melting furnaces, hot metal pretreatment furnaces, VOD furnaces, soaking furnaces, hot blast furnaces, and the like.

[Prior Art] A blast furnace is a high-temperature metallurgical reactor that uses an iron oxide raw material such as iron ore and a solid reducing agent such as coke, and is composed of a thick refractory layer and an iron shell surrounding the thick refractory layer. However, the inside of a blast furnace is extremely hot and is constantly subjected to falling impact and friction from iron ore and coke, so the fireproof wall erodes or falls off in various places, and the steel shell is perforated each time to remove the fireproofing agent. Performing injection repairs. However, the reality is that it is not possible to accurately detect the state of wear and tear on fireproof walls, and in the past there were even cases where people relied on primitive means of knowing when the steel skin turned red. For this reason, research has been widely conducted to try to understand the current thickness of fireproof walls logically.For example, the method introduced below (Japanese Unexamined Patent Application Publication No. 51-197) is a method for calculating the thickness of fireproof walls using heat flux. 29951) is also known.

As shown in Fig. 2, this method involves inserting a thermometer into the blast furnace refractory wall to measure the temperature at two different points in the thickness direction, and measuring the temperature j+ at a depth of a from the shell. , and the temperature t2 at a depth position b from the iron skin C to determine the fireproof wall thickness X based on the following calculation formula. Two of the fireproof walls are made of chamotte bricks and are made of cushioning material. By the way, if the fireproof wall temperature is T, then to the thermometer,
The heat flow rate Q between the temperature measurement points is expressed by λ: thermal conductivity.

Therefore, by estimating the fireproof wall inner surface temperature T, the fireproof wall thickness X can be determined.

[Problems to be Solved by the Invention] However, in the above method, the inner surface temperature T of the refractory wall is estimated and is assumed to be a constant value regardless of the situation inside the furnace. However, in actual blast furnace operation, fluctuations in the rising gas flow and load Changes can be seen in the reaction inside the furnace due to downward fluctuations, and not only the reaction situation often fluctuates, but also the behavior of the inner surface of the refractory wall is complicated and is affected by the falling charge and fluctuations in the gas flow. The internal temperature of fireproof walls fluctuates widely, and there is a problem in estimating it as a constant value. Furthermore, it is of course impossible to measure the inner surface temperature T of the fireproof wall with the two-point thermometer described above.

Therefore, the estimation of T in equation (2) becomes inaccurate, and tl
Even the estimation of the fireproof wall thickness X calculated from the data of t2 and t2 is extremely unreliable.

The present invention has been made with attention to such a situation, and an object of the present invention is to establish a method by which the thickness of a fireproof wall can be accurately determined regardless of fluctuations in operating conditions.

[Means for Solving the Problems] However, the method of the present invention is to install a temperature detection sensor having three or more temperature sensing parts in the longitudinal direction on the refractory wall of a high-temperature furnace, facing the thickness direction of the wall, and using a state-of-the-art method. The temperature sensing part is buried in the furnace so that it is exposed and measures the temperature inside the furnace and the temperature inside the fireproof wall. The gist is that the heat flux Qij in the wall thickness direction between the hot sections is calculated, and the refractory wall thickness X is determined as a function that is inversely proportional to the calculated heat flux Qtj and proportional to the furnace temperature.

[Operations and Examples] FIG. 3 shows an example of a temperature detection sensor that is applied to the present invention and has six temperature sensing sections in the longitudinal direction (a temperature detection sensor proposed by the present applicant in 1983). 16816), and FIG. 4 is a developed cross-sectional view corresponding to FIG. 3. In the figure, 1 is the outer sheath tube, which serves as a protective tube for the entire sensor B. 2a is a sheath type thermocouple, which can of course be replaced with a sheath type resistance thermometer. Passed through the thermocouple 2a are a pair of metal wires 4, 4' exhibiting a thermoelectric effect, the tips of which are located within the sheath as measurement contacts, ie, temperature sensing portions T, T2.・
...Ts, T6 (hereinafter referred to as T when speaking representatively) constitutes. These temperature sensing parts T are configured to occupy different positions in the length direction, and in the figure, the positions in the length direction are changed at approximately equal pitches from the inside of the furnace to the side of the shell.

T2. ...T6 is provided. This pitch is arbitrary, and of course may be random, but a preferred design example would be to reduce the pitch between the temperature-sensitive parts inside the furnace in order to improve the accuracy of estimating the degree of wear on the refractory type. . A sheathed thermocouple 2b made of the same material as the sheathed thermocouple 2a is connected as a dummy to the tip of the temperature sensitive part T (6 in the figure indicates a connection part). Therefore, since the geometric cross-sectional configurations of the sensors B are exactly the same, the thermal conditions, that is, the temperature measurement conditions at each temperature sensing portion T are constant.

Further, 3 is a fire-resistant insulating material filled in the outer sheath tube 1, which ensures the durability of the sheathed thermocouple 2a and reduces heat transfer in the length direction within the sensor B. This increases the accuracy of temperature measurement in the length direction. In order to reduce heat transfer in the longitudinal direction, it is recommended that the outer sheath tube 1 be made of a thin-walled tube made of a material with low thermal conductivity.If corrosion resistance is also taken into consideration, stainless steel or Inconel etc. is desired.

In this way, in combination with the strength effect based on the characteristic structure of the double-sheathed tube, the temperature measurement at each temperature sensing part P, which is a prerequisite for heat flow calculation, can be carried out reliably and with high precision over a long period of time.

Other examples of the above-mentioned sensor B (sensor B' of Utility Model Application Publication No. 57-81531 proposed by the present applicant) are shown in Fig. 5 (partially cutaway sketch) and Fig. 6 (Fig. 5). Vl
-Vl line sectional view). That is, sensor B' has each temperature sensing part TI, T2, . . . of sensor B as described above.
- A disc-shaped fin 8a corresponding to.

8b, . . . and each disc-shaped fin Ba.

8b, . . . are isolated from each other by an insulating material 10, and further covered with a protective outer tube 11 and a blind plate 12 made of a heat-insulating high-strength material. Therefore, if such a sensor B' is used, it is possible to measure the temperature reliably and with high precision even when deposits are generated or grown on the inner surface of the fireproof wall, which is convenient.

・Figure 1 is a longitudinal cross-sectional explanatory diagram showing a situation where temperature detection sensor B' of the temperature detection sensors mentioned above is buried in the blast furnace refractory wall, and the temperature sensing parts TI and T2 at the tip of the sensor are exposed inside the furnace. The temperature sensing parts T, -T6 are embedded in the fireproof wall and measure the temperature inside the furnace and the temperature inside the fireproof wall.

The method of the present invention will be explained below based on FIG. 1, but it goes without saying that this figure shows one embodiment and the present invention is not limited thereto.

In the present invention, the heat flux Qij between adjacent temperature-sensing parts in the fireproof wall is calculated by the above-mentioned sensor, and it is desirable to select two points near the inside of the furnace from among the temperature-sensing parts in the fireproof wall for Qij. In the illustrated example, Q34 was calculated.

t, , : Temperature measurement value at Ts t4: Temperature measurement value at T4 J134: Distance between T3 and T4 λ34: Thermal conductivity between T3 and 14 On the other hand, the heat flux Q penetrating the fireproof wall is expressed by the following equation (4) It is expressed as

8t: Temperature of the inner surface of the fireproof wall (t=tl=t2) to: Temperature of the outer surface of the steel shell .

From (4), X can be found.

That is, the temperature t of the outer surface of the iron skin. is close to the outside temperature and does not vary greatly, and the thermal conductivity λB is a known value, so
The internal temperature of the fireproof wall and the heat flux Q34 between T3 and T4
If this is known, the fireproof wall thickness X can be determined. That is, the refractory wall thickness X can be determined as a function that is inversely proportional to the heat flux Q34 and proportional to the refractory wall inner surface temperature (furnace temperature) t.

By the way, t3 and t obtained by the above temperature detection sensor
The heat flux Q34 was calculated from the temperature measurement data of No. 4, and the results shown in FIG. 7 were obtained when the estimation was investigated. Such fluctuations in the heat flux Q34 are due to fluctuations in the furnace condition, that is, the furnace temperature t, but in the conventional method, the furnace temperature t is kept constant, so as can be understood from equation (5). Heat flux Q34
The fireproof wall thickness X varies significantly due to the variation in the fireproof wall thickness, making it impossible to accurately grasp the fireproof wall thickness. In contrast, in the present invention, since the temperature inside the furnace, that is, the internal temperature of the refractory wall, can be accurately determined, the thickness of the refractory wall can also be accurately determined.

On the other hand, when formula (5) is transformed, it becomes as follows.

Here, since t-to :t can be considered, it becomes X, and an inversely proportional relationship is established between Q34/t and X. Therefore, in order to verify this relationship, we conducted Q3 over a long period of time.
When the correlation between X and Q34/l obtained from the results of 4 was plotted on a graph, Figure 8 was obtained. As shown in FIG. 8, it has been proven that a correlation exists between X and Q34/l, and the fireproof wall thickness X can be estimated from the value obtained by correcting Q34 by t.

Furthermore, in equations (3) and (4), assuming 4=λ8, 34X is obtained, and by transforming this, the following is obtained.

That is, it is possible to estimate the fireproof wall thickness X from the temperature measurement data at T1 or T2 and the temperature measurement data at T, T4 in the temperature detection sensor.

In the above example, temperature detection sensor B' (example in Figures 5 and 6)
Temperature detection sensor B (Example in Figure 3-4)
The present invention can be applied to any temperature detection sensor that has three or more temperature-sensing parts in the longitudinal direction and whose tip protrudes into the furnace and is capable of measuring temperature. It can be applied to

[Effects of the Invention] The present invention is configured as described above, and the fireproof wall inner surface temperature T
Since the heat flow inside the refractory wall can be measured continuously and accurately, the thickness of the refractory wall can be accurately determined from the outside as a function that is proportional to the internal temperature of the refractory wall and inversely proportional to the heat flow. In this way, blast furnace operation can be maintained stably, and if necessary, the firewall can be repaired to extend its life.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional explanatory diagram for explaining the method of the present invention, Fig. 2 is a cross-sectional diagram for explaining the conventional fireproof wall thickness measuring method, and Fig. 3 is a temperature detection sensor B applied to the present invention. Fig. 4 is a partially cutaway perspective view of the same sensor;
The figure is a partially cutaway perspective view of another temperature detection sensor B'.
The figure is an explanatory cross-sectional diagram of the same sensor, Figure 7 is a graph showing changes in heat flux Qij, and Figure 8 is a graph showing the fireproof wall thickness X and Q34/
It is a graph showing the relationship between t. 1... Mantle sheath tube 2... Sheathed thermocouple 3.
... Insulating material 4 ... Metal wire 8 ... Disc-shaped fin 11 ... Protective outer tube 12 ... Blind plate

Claims (1)

[Claims] A temperature detection sensor having three or more temperature-sensing parts in the longitudinal direction is buried in the refractory wall of a high-temperature furnace, facing in the wall thickness direction and with the most advanced temperature-sensing part exposed inside the furnace. While measuring the internal temperature of the fireproof wall, the wall thickness direction heat flux Qij between adjacent temperature sensing parts is calculated based on the temperature measurement results detected by two or more temperature sensing parts in the fireproof wall, and the calculated heat flux is calculated. A method for determining the wear status of a high-temperature furnace refractory wall, characterized by determining the refractory wall thickness X as a function that is inversely proportional to Qij and proportional to the furnace temperature.