JPS59137783A - Method of measuring depth of electrode in sealed electric furnace - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables the reduction and refining of various ores using a closed electric furnace, such as in the production of ferroalloys, to each pole side without interrupting the operation or performing positive current/opening. The present invention relates to a method that can quickly and accurately measure the electrode depth (i.e., electrode tip position).

FIG. 1 is a schematic vertical cross-sectional view illustrating a refining operation using a closed electric furnace.

The upper inner surface of the furnace wall 1 is made of chamots refractory brick, and the lower inner surface is made of carbonaceous refractory. The ore in the raw material A (ore and coke) charged from the raw material charging port 4 is melted by the resistance heat generated by applying electricity to the electrode 2 (usually 8 self-firing electrodes are used), and the coke and semi-molten material are melted. H
Reduction refining progresses in the coke bed C1 due to the difference in specific gravity.
Separates into slag and coke S and molten metal M. In the figure, 8 indicates a furnace lid, 5 indicates an exhaust gas duct, D indicates deposits, and 10 indicates a regularly opened outlet. The amount of heat required to operate this Kaede electric furnace is the heat to melt the raw material, Fe
The heat is divided into heat for reducing oxides such as XM n % 81, and heat for imparting fluidity to the molten metal or slag, but most of these are supplied by resistance heat generated near the tip of the electrode.

When the electrode tip is in the optimal position, the heat that contributes to the melting of raw materials, reduction reactions, and improved fluidity of products is distributed in a well-balanced manner, making the most effective use of the supplied power and improving the yield of Mn, etc. is also maximum. By the way, if the electrode tip is not in the correct position, the heat balance that contributes to the above-mentioned melting, reduction, and flow will be disrupted, leading to overheating in some areas and insufficient heat in other areas, which will significantly reduce operating efficiency, including power consumption. It's going to decline. In this sense, it is extremely important to accurately know the position of the tip of the electrode (ie, electrode depth L in FIG. 1) in electric furnace operation. In order to meet this demand, for example, the method of measuring the position of the tip of Kaede's electrode as shown below has been proposed, but each method has the following problems and is hardly satisfactory.

■Open the electric furnace, insert the iron rod through the opening in the sloped part of the furnace lid, search for and confirm the end of the roof, and use trigonometry to calculate the position of the electrode tip from the angle between the horizontal line and the iron rod and the length of the insertion.

This method requires the interruption of electric furnace operation and the opening of the furnace lid, making the measurement work difficult. Furthermore, many workers must work in close proximity to the open electric furnace, resulting in safety concerns. However, there are problems with this, and furthermore, it is not possible to measure continuously.

■A method in which a steel pipe with a carbon rod inserted in the longitudinal direction is passed concentrically into the electrode, and the electrode depth is determined by the propagation time of the reflected wave when high-frequency electromagnetic waves are transmitted through the carbon rod.

In this method, the strength of the electrode decreases due to the insertion of the steel pipe,
Electrode breakage is likely to occur during operation. Moreover, because highly concentrated CO gas leaks out of the furnace through the steel pipes, there is a risk of poisoning or ignition and explosion.

■As illustrated in Japanese Patent Application Laid-open No. 56-66687, a temperature measurement sensor is inserted into the raw material layer through the furnace cover, and is raised and lowered to detect a temperature range of 1200°C.
A method for estimating the electrode tip position based on this position.

In this method, the sensor is easily damaged by melting due to U-temperature gas blowing, slag blowing up, etc. Furthermore, since the sensor must be moved up and down within a hard raw material layer, the sensor is easily damaged mechanically. It requires large equipment and power, and moving parts are prone to failure.

In addition, it is difficult to seal the sensor and the furnace lid, so the risk of poisoning or explosion due to gas leakage cannot be ruled out.

In view of the above-mentioned circumstances, the inventors of the present invention have developed a method for quickly and accurately measuring the electrode depth without the need for interrupting the operation of the electric furnace or opening the positive current, and without causing any other obstacles. We have been conducting intensive research to establish technology that can do this.

As a result, it was confirmed that the depth of the electrode, that is, the position of the electrode tip, can be determined continuously and almost accurately using the temperature of the gas generated during operation of the electric furnace, the CO content in the gas, and the electric resistance value inside the furnace. However, the present invention was completed in an eclipse.

That is, the electrode depth measuring method according to the present invention is based on the temperature of the gas generated from the electric furnace and the CO content (P) in the gas.
Determine the electrode depth index (X) using formula 19 below.The relationship between the electrode depth index (X) and the electrode depth is determined in advance using the electrical resistance value in the furnace as a parameter, and in actual operation The gist lies in determining the electrode depth from the required electrode depth index (X).

X=α・T×β・P+γ CII α, β, γ
DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation and effects of the present invention will be explained in detail below with reference to the drawings of the embodiments. FIG. 2 is a schematic cross-sectional explanatory diagram showing an example of operation according to the present invention, and since the basic configuration is the same as the example shown in FIG. 1, the same parts are given the same reference numerals. However, in carrying out the present invention, the electric furnace equipment is provided with a means for detecting the temperature of the gas generated in the furnace, a means for analyzing the CO concentration in the generated gas, and a means for measuring the electric resistance in the furnace, and information obtained from each means is provided. is input to a calculation/analysis device (not shown), and the electrode depth (1,) is configured to be detected as described in detail below. That is, in the figure, a gas temperature detection sensor 6 is arranged in the upper cavity of the electric furnace to constantly observe the gas temperature, and a generated gas extraction pipe 7 is also inserted in the upper cavity to collect the generated gas (not shown). Directed to the concentration measuring device and constantly connected to the co
ill! It is possible to measure the degree. The position 1- of the gas temperature detection sensor 6 and the generated gas extraction pipe 7 is not particularly limited, but as shown in FIG. It is preferable to arrange it at the rear part of the electrode (shaded area in Fig. 8) which spreads in a fan shape at an angle of 60 degrees to both sides with reference to the straight line K connecting center point q of the electrode 2 from a to the center point q of the electrode 2. is immediately behind each electrode 2 on the straight line.

The reason for this is that this area is the least susceptible to being affected by other Den & 2 attacks. However, the generated gas extraction pipe 7 for measuring the CO concentration does not necessarily need to be installed for each electrode, and may be representatively placed at one point at the inlet of the duct 5 where all the generated gas is discharged. In addition, an ammeter and a power consumption meter are attached to the power supply equipment connected to each electrode 2 (
(Both drawings omitted), the electrical resistance inside the furnace can be measured from these measured values. Although it is possible to separately install a resistance meter in the furnace as a means for measuring electrical resistance inside the furnace, the above-mentioned means is preferable from the viewpoint of equipment maintenance. Also, instead of this resistance value, this and a high 4-mesh coefficient (90
% or more)' The power factor of the power supplied to the f4i pole may be used.

In measuring the electrode depth (L) during operation in this electric furnace equipment, the above-mentioned CI), the electrode depth index (
X) is determined, and this value is converted into an electrode depth (L) using the in-furnace electrical resistance value as a parameter. That is, the electrode depth index (X
) and the electrode depth (L), there is a linear relationship depending on the in-furnace electrical resistance value, so a regression line is determined by conducting a number of experiments in advance. For example, FIG. 4 shows a regression line obtained in a preliminary experiment when producing silicomanganese in Furnace 2 in Table 1, and the regression line shows the primary old line.

Therefore, the ill depth index (x) calculated from equation 19 is calculated based on the gas temperature ■ and the measured value of the CO concentration in the gas, and this is applied to the regression line according to the measured value of the electrical resistance inside the furnace. Then, the electrode depth (L) can be determined. As mentioned above, the constants α, β, and γ in Equation 19 are determined by the type of electric furnace, operating conditions, charging material, etc., and these coefficients were also determined through preliminary experiments. do.

For example, Table 1 below shows the results of an electrode depth measurement experiment when producing silicomanganese using two types of electric furnaces, and shows the relationship between the electrode depth index (X) and the electrode depth (L). The regression line in Figure 4 was used for the conversion. For comparison, as is clear from Table 1 of the actual measurements obtained using the conventional method (2), the method of the present invention can almost accurately measure the electrode depth with an extremely small error of within 8%. In addition, a large number of experiments were conducted with various changes in the charging material and operating conditions, but in each case, preliminary experiments showed that the regression line according to the electrical resistance in the furnace and the coefficients α, β, and γ of [Equation 13] were It has been confirmed that the electrode depth (L) can be accurately measured with an error of 5% or less at most, and 8% or less in most cases.

The present invention is roughly configured as described above, and although the creation of the regression line through preliminary experiments and the setting of the constants α, β, and γ of Equation 13 are complicated, these steps are strictly required. Later, the electrode depth can be measured extremely quickly and accurately by simply measuring the gas temperature, CO concentration, and electrical resistance in the furnace during actual operation. Moreover, as listed below
All of the problems that had been pointed out in the conventional method could be resolved, and the operating efficiency of the electric furnace could be improved, as well as the electric power consumption rate could be significantly reduced.

■Measurements can be carried out without the need for positive electricity or door opening, which eliminates the burden of labor and risk on workers.

■Since the electrode depth can be measured continuously at short intervals during operation, the electrode tip can always be adjusted to the optimal position according to electrode wear, etc., greatly improving operational efficiency and power consumption. be done.

■Since the measuring equipment only needs to be fixed to the furnace lid, damage to the equipment is drastically reduced compared to the conventional method of raising and lowering sensors, etc., and since the sealing is easy, there is no risk of gas poisoning due to leakage of gas inside the furnace. There is no concern that it will cause an explosion.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional diagram showing an example of operation of a normal closed electric furnace, FIG. 2 is a schematic cross-sectional diagram showing an embodiment of the present invention, FIG. 3 is a schematic cross-sectional diagram of an electric furnace, and FIG. It is a regression line graph illustrating the relationship between the electrode depth index and the electrode depth using the in-furnace electrical resistance as a parameter. 1. Electric furnace wall, 2. Electrode, 8. Furnace lid,
4. Raw material charging port, 5. Exhaust gas duct, 6
Gas temperature detection sensor, 7... Gas extraction pipe, A... Raw materials (ore and coke), C... Coke bed, s... Slag and coke,
L Electrode depth.

Claims (1)

[Claims] When operating a closed electric furnace, the temperature α) of the gas generated from the electric furnace and the CO content Φ) in the gas are measured, and the electrode depth index 1, X) is calculated from the following CI) formula. To calculate the relationship between the electrode depth index (X) and the electrode depth, the relationship between the electrode depth index (X) and the electrode depth is determined in advance using the in-furnace electrical resistance value as a parameter, and the electrodes on each side of each pole are determined from the electrode depth index (X) determined in actual operation. A method for measuring electrode depth in a closed electric furnace, characterized by determining the depth. x= a*T+l/@P+r -CI) However, α,
β and γ are constants determined by the type of electric furnace, operating conditions, charging materials, etc.