JPH0447003B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method and device for detecting fluidization of a burden, and is a method for detecting fluidization, which is a phenomenon that inhibits stable descent of a burden, which is important in the operation of a blast furnace. This is a detection technology that can be applied to metallurgical furnaces using shaft furnaces.

[Conventional technology]

Stable burden descent is an essential condition for blast furnace operation. While the gas flow rate in the blast furnace is low, the buoyancy force that floats the gas charge is smaller than the weight of the charge itself, and has no effect on the descent of the charge. The buoyancy of the charge due to gas is 1.7 of the gas flow rate.
Since it increases in proportion to the power of the gas flow rate, it increases rapidly as the gas flow rate increases. When the buoyancy caused by the gas begins to overcome the weight of the charge, the charge begins to fluidize, making it impossible to expect the charge to descend smoothly.

In order to detect such fluidization, the measured value of a pressure gauge attached to the shaft was conventionally used (Japanese Patent Publication No. 53-19217).

This detection method calculates the ratio between the pressure loss 〓P/〓L in a certain section in the height direction of the blast furnace and the dead weight of the charge in that section, and when this ratio is 1 or more, it is judged that the fluidization state is present. This is the way to do it. If the charge is uniform and the pressure loss is constant in the height direction of the blast furnace, accurate detection can be achieved with this conventional method.

However, ores and coke with different ventilation resistances are usually charged in layers in a blast furnace, and the grain sizes (airflow resistance) also differ in the radial direction, so even if the ratio of pressure loss to dead weight is less than 1, The internal contents start to fluidize locally. Therefore, in actual fluidization detection, fluidization is determined when the ratio of pressure loss to dead weight exceeds a certain reference value of 1 or less. In other words, the phenomenon of fluidization in the furnace has conventionally been determined indirectly from the magnitude of pressure loss. The reference value is determined empirically by determining the relationship between the burden descent state and pressure loss from operational data. However, there is usually no clear correspondence between the pressure loss and the falling state, and this relationship has the disadvantage that it includes the influence of factors other than fluidization. On the other hand, a method of inserting two electrodes into the blast furnace charge and measuring the resistance between them was published in JP-A-52-
14447, or as shown in Japanese Patent Application Laid-Open No. 53-18408. This is a technology that primarily uses the difference in electrical resistance between ore and coke to determine the thickness and rate of descent of each layer.

[Problem that the invention seeks to solve]

The present invention maintains the fluidization state of the contents in the blast furnace, rather than using indirect methods such as pressure loss as described above.
The purpose of this is to detect and improve localized fluidization in the furnace at an early stage by directly detecting it with an electrode inserted into the charge.

[Means for solving problems]

In order to directly capture the phenomenon of fluidization, it is necessary to utilize the characteristics of fluidization inside the blast furnace. As a result of various studies conducted through model experiments, the inventors found that when fluidized in a layer with coarse grains and a high layer height, such as in a blast furnace, a slugging state occurs. The slugging state is a state in which large voids repeatedly appear, rise, and disappear periodically.

The characteristic technical means of the present invention is to capture this characteristic of fluidization by changing the electrical resistance between electrodes inserted within the layer. In other words, the method of the present invention inserts a specific pair of electrodes into a blast furnace, analyzes changes in electrical resistance between the electrodes, and compares the analyzed value with a reference value to determine the flow of the contents in the furnace. Determine the occurrence of oxidation phenomenon. To do this, (1) use electrodes larger than a certain limit that can clearly capture changes in the state inside the furnace, and (2) process the obtained electrical signals to extract the characteristics of fluidization. It becomes necessary to determine fluidization based on

In the present invention, periodic changes in the layer structure accompanying fluidization are captured by electrical resistance. For this purpose, a sufficiently large grounding electrode and a detection electrode of a certain size are combined and the electrical resistance between the electrodes is measured.

FIG. 1 is a block diagram of a first embodiment of the apparatus of the present invention, which can suitably carry out the method of the present invention.

The detection electrode 1 and the grounding electrode 3 are integrally formed with an insulator 2 in between, and form a rod-shaped measurement terminal, for example, so that it can be easily inserted into the furnace from the furnace wall.

A resistance measuring device 10 is connected between the detection electrode 1 and the grounding electrode 3 to apply a DC voltage and measure the resistance between both terminals. Between the detection electrode 1 inserted into the furnace and the grounding electrode 3, conductive particles made of coke, ore, etc. (not shown) form an electrical circuit with resistance. In order to maintain sufficient contact with these particles, the width of the exposed surface of the sensing electrode is set to a certain value or more, as will be described later.

The resistance value measured by the resistance measuring device 10 is input to the frequency analysis device 11. A known device may be used as the frequency analysis device. This frequency analysis device 11 spectrally analyzes changes in the input electrical resistance. 0.05 of its spectrally analyzed output
The fluidization determination device 12 detects the high value of energy density of the electrical resistance waveform that exists between 5 Hz and grasps the fluidization state.

A second method that can suitably carry out the method of the present invention
The device of the present invention includes a pulse generator instead of the frequency analyzer of the first device, and the fluidization determining device analyzes and determines this pulse. That is,
The pulse generator receives the measured value of the resistance measuring device 10 as input, and outputs as a pulse the value when the electrical resistance is higher than a certain value. The fluidization determining device determines the occurrence of fluidization when the pulse rate is, for example, 3 times/min or more.

In the first and second devices of the present invention, in order for the detection electrode 1 to maintain suitable contact with the contents in the furnace and to ensure the measurement accuracy of the device of the present invention, the detection electrode 1 must have a surface area of at least a certain level. A round bar with a diameter and exposed length that is 0.5 to 10 times the harmonic mean diameter of the conductive particles in the blast furnace charge exhibits an excellent effect.

Figure 2a shows the change in electrical resistance of the coke layer under normal conditions, Figure 2b shows the change in electrical resistance during fluidization, and Figure 2c shows the change in electrical resistance when an insufficiently large electrode is used. The electrical resistance changes are shown for each case.

[Effect]

Next, the operation of the method and apparatus of the present invention will be explained using FIGS. 2 to 5.

When the coke layer in the furnace is in a normal state, that is, when it is not fluidized, there is electrical continuity between the sensing electrode and the grounding electrode due to the coke, as shown in Figure 2a. It constantly exhibits a certain level of electrical resistance. However, when the coke layer becomes fluidized, as shown in FIG. 2b, it begins to exhibit extremely high resistance peaks intermittently. When the size of the electrode is insufficient, a resistance change as shown in FIG. 2c occurs, and it is not possible to determine whether the normal state is a flowing state.

In order to determine the size of the electrode that can clearly distinguish between the two states shown in Figure 2 a and b, experiments were conducted by varying the length of the detection electrode and the diameter of the coke, and the relationship shown in Figure 3 was found. I understand. The white circles in FIG. 3 indicate the case where the two states a and b in FIG. 2 can be distinguished. To detect fluidization, the size or thickness of the detection electrode should be 0.5 times the coke diameter.
A range of 10x is appropriate. Furthermore, it has become clear that a range of 1 to 5 times the coke diameter is most desirable. If the electrode size is less than 0.5 times, the electrical resistance of the coke layer cannot be stably measured, and if the electrode size is larger than 10 times, periodicity will not appear. The periodic change in electrical resistance as shown in FIG. 2b is unique to fluidization and can be easily distinguished from changes in electrical resistance in ore layers and mixed layers. The following two methods and devices are used to quantitatively evaluate this using electrical signal processing.
There is one.

(1) When an electrical signal is analyzed using a spectrum analyzer, a spectrum as shown in Figure 4 is obtained. As shown in FIG. 4, when the contents in the blast furnace are fluidized, a characteristic peak appears between 0.05 and 5 Hz. The frequency at which this peak appears varies depending on the diameter of the fluidized region, and has a relationship as shown in FIG. Considering the size of a normal blast furnace, it can be seen that the peak in the range of 0.05 to 5 Hz should be targeted. Furthermore, it can be seen from FIG. 5 that the diameter of the fluidized region is larger when the frequency is smaller than when the frequency is larger. By comparing the peak of the spectrum during this period with a reference value, fluidization of the charge in the blast furnace can be quantitatively determined.

(2) Another method of processing electrical signals is to output pulses according to the high value of the resistance between the electrodes, directly count this periodic signal, and use the coefficient value as the standard, without performing spectrum analysis. The fluidization of coke in the furnace is determined quantitatively by comparing the values.

〔Example〕

Example 1 FIG. 6 shows an example in which the present invention was carried out by setting the electrode according to the present invention on a measuring rod called a horizontal sonde in the radial direction inside the blast furnace. The tip is the sensing electrode 1, and the grounding electrode 3 is the measuring rod itself in this case. The diameter of the detection electrode 1 is 30 mm, which is 1.5 times the harmonic mean diameter of 20 mm of the coke in the furnace, and the length is 50 mm, which is 2.5 times the harmonic mean diameter of the coke in the furnace. A ground electrode 3 is located at the base of the detection electrode 1.
A refractory material 2 is thermally sprayed to prevent short circuits. It is connected to an electrical resistance measuring device 10 outside the furnace using an insulated sheathed wire 7 while preventing a short circuit with a ground electrode. _N2 purge inside the sonde to prevent short circuit between electrodes due to coke powder
doing.

FIG. 7 shows an example in which this sonde was inserted into the shaft portion of the furnace center and around the furnace wall to detect fluidization.

In this case, the peak of the frequency spectrum is
Since it appeared near 0.5Hz, it shows the transition of this peak. Before the air flow rate was increased, no peak values appeared between 0.05 and 5 Hz in both the center and periphery areas. When the air flow rate was increased, a peak appeared around 0.5Hz at the center, and the peak value also increased rapidly. On the other hand, no peak appears in the peripheral area. The peak in the center then disappeared due to a decrease in air flow. By setting a reference value with a certain bias in the waveform analyzer to prevent noise, we were able to automatically and clearly detect fluidization in the center.

Example 2 FIG. 8 shows the results of fluidization detection by directly counting periodic signals without performing spectrum analysis. The electrodes and the electrical resistance measuring device are the same as in the embodiment shown in Figure 6, and instead of the frequency analyzer, a pulse generator that generates a pulse when the resistance exceeds a certain value and a pulse generating device are used. A judgment device was installed to count and compare with the standard number of times.

Fig. 8 shows the actual measured value of the resistance value and the pulse outputted with 50〓 of the actual measured value as a reference value.
15 pulses are emitted in 10 seconds, and 1 of these
This corresponds to the peak value unique to fluidization, except for times. FIG. 9 shows the transition of the results of counting long-term pulses. Ten hours after the start of measurements, the number of measurements increased rapidly, and it was detected that the inside of the furnace had become fluidized.

As shown in FIG. 2a, the electrical resistance of coke at the base line in the normal case is about 10 to 10. On the other hand, the change in electrical resistance caused by fluidization periodically changes between the electrical resistance of the coke layer and the resistance of the insulating state (several M〓). As can be seen from the spectrum analysis mentioned above, this period is
It is between 0.05 and 5Hz. Therefore, a value obtained by multiplying the electrical resistance of the coke layer by a certain constant (for example, about 20) is set as a reference resistance value, and the number of times the resistance changes beyond this reference value is counted. The fact that the period is 0.05 to 5 Hz indicates that fluidization can be determined if the count is at least 3 times/minute or more. In other words, a reference resistance value is determined by multiplying the resistance value of the coke layer by a certain value, the number of times the resistance value exceeds this reference value within a unit time is counted, and that value is compared with the reference number of times of 3 times/minute or more. This makes it possible to detect fluidization within the furnace. This method can be realized by a pulse generator, and has the advantage of being inexpensive because it uses a waveform analyzer like method 1 above.

In the above explanation, a blast furnace has been described, but the present invention is also applicable to direct reduction of iron using a moving bed type reactor filled with a conductor, such as a coke packed bed.
It can be applied to detecting fluidization in Cr reduction equipment. It can also be applied to detecting fluidization in the lower part of a direct reduction furnace using a shaft furnace (the area where metallic iron comes out).

〔Effect of the invention〕

According to the present invention, it has become possible to directly detect fluidization and detect local fluidization in a blast furnace, which was impossible with conventional methods and devices. Detection of cage fluidization makes it possible to take early action to prevent fluidization, thereby preventing problems in blast furnace operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the device of the present invention;
Figure 2 is a graph showing the types of electrical resistance waveforms;
Figure 4 is a graph showing an appropriate electrode size, Figure 4 is a graph showing an example of frequency analysis, Figure 5 is a graph showing the peak position and the size of the fluidized region, Figure 6 is a block diagram of an example, and Figure 6 is a graph showing an example of frequency analysis. FIG. 7 is a graph of an example of fluidization detection, FIG. 8 is a chart of an example, and FIG. 9 is a graph of an example. 1...Detection electrode, 2...Insulator, 3...Grounding electrode, 4...Water supply and drainage, 5... _N2 purge, 6...
...Cylinder, 7...Sheathed electric wire.

Claims (1)

[Claims] 1. A charge flow method characterized by analyzing changes in electrical resistance between a pair of electrodes inserted into a blast furnace, and determining a fluidization phenomenon of a charge in the furnace from the analyzed value. Detection method. 2. A measurement terminal inserted into the furnace, in which a detection electrode and a grounding electrode are integrally formed via an insulator, a device for measuring electrical resistance by applying a DC voltage to the measurement terminal, and a spectrometer for measuring changes in electrical resistance. A charge fluidization detection device comprising a frequency analysis device for analysis and a fluidization determination device for detecting a high value of energy density of an electrical resistance waveform existing between 0.05 and 5 Hz. 3. The fluidization detection device according to claim 2, wherein the detection electrode has a diameter and length that are 0.5 to 10 times the harmonic mean diameter of the conductive particles of the blast furnace charge. 4. A measurement terminal inserted into the furnace in which a detection electrode and a grounding electrode are integrally formed via an insulator, a device that measures electrical resistance by applying a DC voltage to the measurement terminal, and a device that measures electrical resistance by applying a DC voltage to the measurement terminal. A pulse generator that converts a value into a pulse and outputs it, and this pulse
1. A charge fluidization detection device comprising: a fluidization determination device that determines fluidization when the rate is equal to or higher than times per minute. 5. The fluidization detection device according to claim 4, wherein the detection electrode has a diameter and length that are 0.5 to 10 times the harmonic mean diameter of the conductive particles of the blast furnace charge.