JPS5850290B2 - Sonde for measuring electrical resistance of contents in reduction melting furnace - Google Patents

Description

Detailed Description of the Invention The present invention relates to a furnace in which coke, sintered ore, pellets, and lump ores (hereinafter referred to as ores) are charged in layers from the top of the furnace, such as a blast furnace or shaft furnace. The present invention relates to the structure of a detection sonde for measuring the thickness of a charge deposit by utilizing the difference in electrical resistance between coke and ore-like layers.

In reduction melting furnaces such as blast furnaces and shaft furnaces, coke and ores are charged discontinuously and alternately in predetermined amounts using a bell-shaped or rotating chute-type furnace top charging device.

FIG. 1 shows a cross section of the main part of the top of the blast furnace according to the present invention.

In this case, in a top charging device using a bell 1, the charge distribution depends on the position of the movable armor 2, and in a rotating chute type charging device, which is also used (not shown), due to the difference in the angle of inclination of the chute. Shape changes.

At the same time, the charge deposition layer thickness in the furnace radial direction also changes significantly.

As a result, the flow of gas in the furnace caused by air being blown from the slats in the lower part of the furnace is greatly affected.

That is, in the thick part of the ore layer with high ventilation resistance, the gas flow is small, and on the contrary, in the thin part, the gas flow is large.

If this gas flow is significantly unbalanced, problems such as shelving, slipping, and gas blow-through may occur, making it impossible to maintain normal operation of the furnace.

Therefore, in order to maintain stable operating conditions, it is necessary to constantly adjust the layer thickness of the charge to obtain the desired gas flow distribution.

As a method of adjusting the layer thickness, there is a method of changing the position of the movable armor 2 in a bell-type charging device, and a method of changing the inclination angle of the chute in a rotating chute-type charging device, but in either case, it is possible to adjust the layer thickness by changing the position of the movable armor 2 in a bell-type charging device. In order to adjust the thickness, it is necessary to reliably measure the thickness of the deposited layer.

A known method for measuring the thickness of the deposited layer is to use the difference in electrical resistance of the charge in the furnace. The coke and ores falling in the furnace are distinguished from each other by being inserted and fixed into the furnace from the furnace wall, and the time during which the coke and ore layers are continuously detected is measured. and a part that measures the time from when the boundary surface of the ore layer is detected by the upper sonde 7 to when the same boundary surface is detected by the lower sonde γ, and the above-mentioned height representing the distance between the sondes 7 and 7' The descending speed of the charge is determined by dividing h by the time difference between the times when the same boundary surface is detected by the two sondes, and the product of this descending speed and the time during which each layer is continuously detected is used to calculate the rate of descent of each layer. This is to find the layer thickness.

Therefore, how to accurately and continuously measure the electrical resistance of the charge is an important point in measuring the layer thickness of the charge in the furnace.

In FIG. 1, 3 indicates a measuring meter and 4 indicates a furnace wall.

Conventionally, this sonde has the structure shown in FIG. 2 a = d.

Figure 2 a and b are used when there are many relatively fine grains with a grain size of 30 mm or less, and Figure 2 c and d are used when there are many coarse grains with a grain size of 30 mm or more. An example of a sonde used is shown, with a and c being radial cross-sectional views, and b and d being longitudinal cross-sectional views.

The conventional sonde shown in Figures 2a-d has a pair of electrodes 10.1.
1 are electrically insulated by an insulating material 12 and configured concentrically, and the central electrode 11 is configured to protrude horizontally toward the inside of the furnace longer than the cylindrical electrode 10. For example, the distance between a pair of electrodes is This method takes advantage of the fact that when the electrical resistance of a coke deposited layer is 40 mm and the electrical resistance is 1 to 3 Ω, there is a large difference between 1000 and 10000 Ω for ores.

However, the measurement using the conventional sonde shown in FIG. 2axd has the disadvantage that the measured electrical resistance of the contents in the furnace changes greatly over time, and after a certain period of time it becomes almost impossible to measure the resistance.

Examples of this are shown in Figures 3a, b, and c. That is, two days after the sonde installation, the coke layer was 1 to 3 Ω, and the ore layer was 800 to 3 Ω.
It shows 1000Ω, but after 20 days, the ore layer is 8
It decreases to 0 to 110Ω, and after 50 days, it becomes around 100, making it impossible to determine whether it is a coke layer or an ore layer, and it becomes impossible to determine the charge layer thickness.

The cause of this is the sonde electrode 10.11 inserted into the furnace.
The insulating material 12 between the electrodes 10 and 11 is damaged and falls off due to thermal shock due to the high furnace gas temperature, impact due to the falling charge, and abrasion, and the fine powder contained in the furnace gas between the electrodes 10 and 11. This is because carbon and small-sized coke in the charge enter, causing insulation failure and reducing electrical resistance to the same level as coke.

The insulating material 12 used in the sonde is used in a high-temperature reducing gas, so the materials that can be used are very limited. ), the above-mentioned breakage and falling-off occur in a short period of time due to the impact when charging the charge into the furnace and the abrasion caused by the falling charge.

The present invention solves these problems and makes it possible to measure the electrical resistance of a charge stably over a long period of time.

FIG. 4 shows an example of the structure of the sonde for layer thickness detection according to the present invention.

In the device shown in FIG. 4, at least one of the electrodes 10, 11 is made of a material having good heat resistance and wear resistance, such as stainless steel, and this electrode 10 is made of an insulating material 1.
The insulating material 12 is shaped so as to cover the whole including the end surface so that the insulating material 12 does not come into direct contact with the charge descending in the furnace, leaving a part of the lower part of the raw end of the second sonde, and the other center electrode 11 protrudes downward into the furnace from below near the tip of the outer electrode 10, and further bends its tip to extend to the same plane as the tip surface of the electrode 10.

In Fig. 4, a shows a side sectional view, b shows a front view, and C shows the fourth
Figure 3 shows a bottom view of the tip section indicated by A-A in figure a, respectively.

It is important to measure the layer thickness and design the space d between the electrodes 10 and 11 inside the furnace shown in FIG. 4 to be approximately the same as the maximum grain size of the intended charge.

This means that if the spacing d is smaller than the grain size of the charge, the electrode 10
．． Since the charge does not pass between the electrodes 11 and 11, the charge and the charge layer may enter and deposit, causing insulation defects, and the electrode 11 may enter the cavity caused by the sonde itself preventing the charge from descending. This is because it may become impossible to measure the electrical resistance of the charged material.

Incidentally, as long as the distance does not remain within the cavity, it is not necessary to make the distance very large.

This is because if this interval is too large, an error will occur in the detection time of the boundary layer between the ore and the coke layer.

Since the present invention has the above-described configuration, it is less likely to be damaged by the charged materials, and stable measurements can be performed over a long period of time.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of the top of a blast furnace, Figures 2 a to d are diagrams showing an example of the structure of a conventional sonde for layer thickness detection, d is a longitudinal cross-sectional view, and a and C are radial directions. Cross-sectional view, Figure 3 a, b, c
4 is an explanatory diagram showing the change in electrical resistance measurement value over time when a conventional detection sonde is used, and FIG. 4 is a diagram showing an embodiment of the present invention, in which a is a longitudinal sectional view, b is a front view, and is a figure A-
FIG. 3 is a bottom view of the tip portion indicated by A; 1... Bell, 2... Movable armor 13... Measuring needle, 4... Furnace wall, 5...
...Coke layer, 6...Ore face, 7 and 7'...Sonde, 10 and 11...
...Electrode, 12...Insulating material.

Claims (1)

[Claims] 1 In a sonde that is inserted into the furnace from the side wall of a reduction melting furnace and then fixed, it is used to distinguish between coke and ores by measuring the electrical resistance of the charge as it descends inside the furnace. A cylindrical electrode 10 configured to cover the entire surface including the tip surface, and an insulator 12 inside this electrode 10.
Another electrode 11 is electrically insulated and concentrically arranged.
The tip of the electrode 11 was made to protrude into the furnace from the notch, and the protruded electrode 11 was bent forward, and the distance d from the electrode 10 was made to be approximately the same as the maximum grain size of the charge. A sonde for measuring electrical resistance of contents in a reduction melting furnace, characterized by: