JPS5952681B2 - Floating layer level detection method in floating steelmaking process - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating layer level detection method in a floating iron making process (floating direct reduction iron making process).

The rotary kiln method, the shaft furnace method, the fluidized bed method, etc. are known as direct iron manufacturing methods, and the present invention is classified into the fluidized bed method.

Conventional fluidized bed methods have advantages such as high reaction rate, uniform temperature in the bed, and easy temperature control, but on the other hand, heat utilization efficiency is low and powder (raw materials) aggregates and adheres, making operation difficult. There are problems such as:

Recently, a floating direct reduction iron making process (floating direct iron making process) has been proposed as a method for solving these problems (Japanese Patent Application No. 157726/1983, etc.).

This floating direct steelmaking process involves floating carbonaceous material (coal, coke, char, etc.) in a furnace maintained at a high temperature (800-1000°C) (with gas), and creating a carbonaceous floating fluidized bed (floating fluidized bed). layer), and in this layer iron oxide raw material (
This is a process in which iron ore powder, etc.) is dropped and reduced while passing through the layer.

For this process, the fluidization flow rate in the furnace is necessarily ○Floating carbonaceous matter ○Falling iron oxide raw materials It is determined by two conditions.

Therefore, the flow rate that satisfies these conditions cannot cover the amount of heat sufficient to maintain the temperature of the floating layer in the furnace at a high temperature, and furthermore, the amount required in terms of material balance is insufficient.

Therefore, in order to cover these two points, that is, ○heat amount ○material balance, by supplying electricity to the carbonaceous floating layer, the temperature in the furnace is increased using the carbonaceous material as a heating medium, and furthermore, Fe2O3+3C= 2Fe +3CO or Fe2O3+ 3 /2C=2Fe+3/2C0
A process has been proposed in which the direct reduction reaction of No. 2 is actively promoted, thereby significantly increasing the productivity of the furnace (Japanese Patent Application No. 51-157727).

In this floating process, one of the conditions for efficient reduction reaction by the floating layer is the floating layer level (layer thickness).
One example of this is to quickly understand the situation.

As a result of various research and experiments, the inventors of the present invention have completed the present invention by noting that the electrical resistance of the floating layer remains approximately constant above a certain temperature, as shown in FIG.

That is, the present invention aims to enable the floating layer level to be detected quickly and easily, and to contribute to the efficient operation of the floating iron making process. In the floating steelmaking process, in which reduced iron is produced by introducing raw materials and allowing them to settle, the electric resistance inside the furnace is measured at multiple heights of the furnace, and the values on each side are determined to be the preset values. The present invention relates to a method for detecting a floating layer level, which is characterized in that the floating layer level is determined from the measured height position when the measured height is a specified value.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 schematically shows an example of an apparatus for carrying out the detection method of the present invention.

1 is a reduction furnace (reaction tower), and at the top of the reduction furnace 1,
Charging system 2 in which iron oxide raw material (iron ore, oxide pellets, etc.) A and carbon granules B as an example of carbonaceous material are charged into the furnace, respectively.
and an exhaust system 3 for discharging the furnace top exhaust gas G.

Further, at the bottom of the furnace 1, there is an introduction system 4 for introducing preheated (or heated) gas (reducing gas) C into the furnace, and reduced iron oxide and char (pre-coking stage) E as products.
An extraction system 5 is provided which separates the two from each other and takes them out.

Furthermore, inside the furnace 1, a plurality of pairs of electrodes 6 are provided along the inner wall of the furnace.

The electrodes 6 are arranged at required intervals in the height direction of the furnace 1, with each pair of electrodes facing each other.

In this example, they are arranged in five rows, starting from the top row: No, 1, No, 2, No, 3, No, 4, No,
5.

An electrical resistance detector 7 is provided in the middle of the wiring connected to the electrodes 6, 6 of each stage, and the electrical resistance detector 7 of each stage performs judgment and calculation based on the measurement signal of each detector 7. It is electrically connected to an arithmetic unit 8 which calculates the floating layer level.

Next, to describe the operation of the iron manufacturing process using this reducing furnace 1, first, during the startup period of the furnace, when preheated (or heated) reducing gas C is blown into the furnace, this reducing gas (reducing atmosphere) C is discharged from the furnace top as furnace top exhaust gas G, and is circulated into the furnace again.

By repeating this circulation, the degree of reduction of the circulating gas increases.

Here, the carbon particles B, which had been charged in advance into the furnace, float in the above-mentioned atmosphere, and a floating fluidized bed of carbon particles B, that is, a floating layer F, is formed in the furnace.

Next, when a voltage is applied between the electrodes 6 and 6 from a power source (not shown), the carbon particles B forming the floating layer F are energized, and the temperature in the furnace is increased by Joule heat.

In this state, when the iron oxide raw material A is introduced into the furnace, it passes through the floating layer F and descends.

When this iron oxide raw material A passes through the floating layer F, the following reduction reaction occurs, and the iron oxide raw material A is reduced by the carbon monoxide in the floating layer F, and the iron oxide raw material A is reduced in a reducing atmosphere containing carbon monoxide, that is, reduced. Gas is regenerated.

The generated reduced iron oxide and char E are separated and taken out, and the char E is sent to the charging system 2 as carbon particles.

Here, a method for detecting the floating layer level (layer thickness) will be explained.

When operating the above-mentioned reduction furnace 1, a prescribed electrical resistance value is determined in advance based on an experiment on a case-by-case basis.

That is, FIG. 1 shows the relationship between the electrical resistance and temperature inside the furnace in the case of this example, and it shows the relationship between the electrical resistance and temperature in the furnace, from about 00°C to about 10°C.
The electrical resistance is a constant value R1 in the temperature range of 00°C.

In addition, the temperature at the top of the floating layer F is usually about 00°C to about 100°C.
0° C., and the temperature below the layer F is lower than that.

This is because Fe has a higher electrical resistance value than carbonaceous material (carbon particles), and since Fe tends to accumulate in the lower part of the layer, the old part of the layer is easily heated.

Therefore, in Fig. 1, the constant resistance section is 600°C to 100°C.
If the electrical resistance value at 0° C. is R1, then R1 becomes the specified value.

The specified value R1 of the electric resistance obtained in this way is calculated by the calculator 8.
Set it to .

Further, the height values of the electrodes 6 at each stage are also set in the calculator 8.

When the above-mentioned operation is performed in this state, the electrical resistance inside the furnace is measured by the electrical resistance detector 7 at each stage during the operation, and the measurement signal is sent to the computing unit 8.

The arithmetic unit 8 determines whether the measured value from each stage is the specified value R1.

For example, in the case of FIG. 2, since the floating layer F is formed under the No. 1 electrode 6, almost no current flows between the No. The measured value is much larger (almost infinite) than the specified value R1.

On the other hand, the measured values of the electrical resistance measuring devices 7 for No. 5 to No. 002 are almost the same (as shown in Figure 1, the electrical resistance values are constant in the floating layer constant temperature range of 600°C or higher). Therefore, it is determined that the value is the specified value R1.

Then, by calculating the height value of the electrode 6 of No. 2 (calculating the difference between the above height values), the layer thickness, that is, the floating layer level can be found (note that the difference between the above height value and the layer thickness is There may be slight errors).

As described above, the detection method of the present invention detects the level of the floating layer by measuring the electric resistance inside the furnace, so the level of the floating layer can be detected quickly and easily. It is easy and accurate to adjust the supply amount and ratio of iron oxide raw materials), and therefore the floating iron making process can be operated efficiently.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between electrical resistance and temperature inside the furnace.
FIG. 2 is a schematic diagram showing an example of an apparatus for carrying out the detection method of the present invention. 1... Reduction furnace, 6... Electrode, 7...
...Electric resistance detector, 8... Arithmetic unit, A...
...Iron oxide raw material, B...Carbon particles, D...
...Reduced iron, F...Floating layer.

Claims (1)

[Claims] 1. In the floating iron manufacturing process, in which iron oxide raw materials are introduced into a floating layer formed of carbonaceous material and allowed to settle to produce reduced iron, the electrical resistance inside the furnace is measured at multiple heights of the furnace, and the Determine whether each side fixed value is a preset specified value,
A floating layer level detection method characterized by determining the floating layer level from the measured height position when it is a specified value.