JPS6360801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a blast furnace operating method that implements burden distribution control using microwave sensors.

[Prior art]

In blast furnaces equipped with movable armor and rotating chute, charge distribution control is an essential means for stable operation of the blast furnace, but its importance becomes even more important under oil-less operation. Efforts are being made to improve the accuracy of
The conventional charge distribution control is a method of moving movable armor and rotating chute based on the gas temperature and gas composition of the shaft sonde installed in the blast furnace shaft. The control accuracy was poor because the determined gas flow was detected indirectly.

On the other hand, in order to improve distribution control accuracy, it is necessary to directly detect the charge distribution, such as the layer thickness ratio of ore and coke, and move the movable armor and rotating chute in a feed forward manner. From this recognition, as seen in Japanese Patent Application Laid-Open No. 56-142809, there is a means to place a magnetic detection element in the charge and use information such as the layer thickness ratio and mixing ratio of the charge obtained from this. be.

On the other hand, the use of microwaves as a means for detecting charge information is shown in Utility Model Application Publication No. 56-151958, etc., for measuring the surface shape of charge charged into a blast furnace. is only for detecting profiles.

The accuracy of control, which uses magnetism to control the distribution based on information such as the layer thickness ratio and mixture ratio of the charges, can be expected to have some effect. However, the charge distribution that determines the gas flow is not only determined by the layer thickness ratio between ore and coke, but also by the grain size of the charge. However, the particle size of the charge could not be detected, so there was a limit to the improvement of control accuracy.

Figure 6 shows conventional control using a sensor that measures the gas temperature near the wall at the top of the shaft.
○A indicates the period when the gas temperature on the 180° side decreased, and ○B indicates the period when an action was taken to reduce the layer thickness ratio of ore and coke on the 180° side. As is clear from this figure, it is not possible to reduce the amount of ore falling to this location by the rotating chute until the gas temperature on the 180° side has decreased, so a period of circumferential imbalance occurs. I know what you're going to do. Similarly, in the case of the center of the furnace, the seventh
An example is shown in the figure. In the figure, there is a period when the gas temperature of the shaft sonde in the center is out of the appropriate range. This is because if the particle size of the charge is small, the gas flow may be suppressed, and conversely, even if the layer thickness ratio of ore and coke is high, if the charge particle size is large, the gas flow may not be suppressed.

[Purpose of the invention]

The present invention solves these conventional problems by proposing a means for obtaining practically useful information with further improved control accuracy.

[Structure of the invention]

The gist of the present invention is to measure the layer thickness ratio of ore and coke at each measurement point and the charge amount using a microwave sensor inserted at an appropriate position in the furnace circumferential direction or furnace radial direction within the charge at the mouth of the blast furnace. The purpose is to detect the particle size of each material and control the distribution of the charging material based on the detected information. The details will be described below based on illustrated examples.

In the present invention, microwaves are used as a sensor that simultaneously detects the layer thickness ratio of ore and coke and the particle size of the charge. For example, it is known in principle that when microwaves are transmitted into the layer from a probe inserted into the layer of a charge, the transmission and reflection performance of the ore layer and the coke layer are different. According to the invention, a probe equipped with a microwave sensor, which is known per se, is inserted into the blast furnace mouth.

FIG. 1 shows one aspect of this, and is a conceptual diagram showing a vertical cross section of the mouth of the blast furnace. In FIG. 1a, 1 is the furnace wall, 2 is the furnace core, 3 is the charge, and 4 is the surface of the charge. 5 is a probe, 6 is a microwave transceiver, and 7 is a signal processing device. In the illustrated example, the height H in the depth direction of the charge 3, which is the insertion position of the probe 5, is normally the position corresponding to one charge of the charge, and the insertion depth L toward the furnace core 2 side is The distance from the brick working surface is usually about 300 to 1000 mm.

When controlling the balance in the circumferential direction of the furnace using these probes 5, a plurality of probes are inserted at approximately equal intervals in the circumferential direction of the furnace. This is illustrated in the conceptual plan view of the furnace in FIG. In this example, four probes are arranged circumferentially offset by 90 degrees. In addition, it is a good idea to insert 8 pieces at 45 degree intervals to further improve accuracy.

Next, the basic cross-sectional structure of these probes 5 is shown in the conceptual diagram of FIG. In FIG. 3a, one transmitting port 8 and two receiving ports are incorporated in one probe in one location. In addition, Fig. 3b shows a set of two wires installed at one location, each with a transmitting port 8.
One receiving port 9 is incorporated.

Microwaves are transmitted into the furnace from the probe transmission port 8 by the transceiver 6, those that have passed through the charge 3 are transmitted through the reception port 9, and those that have been reflected are transmitted through the transmission port 8 to the transceiver. Reach 6. The intensity of the transmitted or reflected microwave is detected by the transceiver 6. The processing of the detected signals is carried out by means known per se, and the ore to coke thickness ratio and the grain size of the charge are determined by the following calculations.

The intensity of the transmitted waves is greater when the charge is ore than when it is coke, and the time change in the intensity of the transmitted waves that have passed through the upper and lower receiving ports as the charge descends is shown in Figure 8. become that way. In Figure 8, Tc
indicates the period during which the charge is coke, T ₀ indicates the period during which the charge is ore, and by calculating T ₀ /Tc, the layer thickness ratio of ore and coke is stated.

In addition, the intensity of the reflected wave is as shown in Figure 9, and the number of peaks per unit time n determined by the cross-point counting method that counts the intersections of the raw signal and the smoothed signal, Δt in Figure 8, and the distance between the upper and lower receiving ports. l to particle size l/
Obtained by calculating Δt·n.

If the layer thickness ratio of ore and coke and particle size information of the charge obtained at each measurement point in the circumferential direction of the furnace are relatively unbalanced, moveable armor or rotating Controls charging conditions using chute, etc. In other words, if the layer thickness ratio between ore and coke is high, the grain size of the charge is small, or both occur at the same time at a certain point in the circumferential direction, the gas flow at this point is suppressed and the reductive heat transfer is inhibited. Due to the delay, the charge may stagnate or grow into deposits, causing poor descent and poor ventilation, which impede stable operation. Therefore, when the above-mentioned unbalance occurs, stable operation can be maintained by resolving the unbalance by changing the extrusion angle of the movable armor in the circumferential direction or changing the amount of fall in the circumferential direction using a rotating chute. can do.

As explained above, in order to catch the gas flow quickly and accurately, information on both the layer thickness ratio of ore and coke and the particle size of the charge is necessary. Also, the reason why multiple tubes are installed in the circumferential direction is to control the circumferential balance, but when the circumference is balanced, the blast furnace will be stable if the peripheral area is controlled. Based. In addition to controlling the circumferential balance, the present invention can be similarly applied to controlling the furnace radial direction. That is, the aforementioned microwave sensor is mounted on a shaft sonde installed in a blast furnace to detect the layer thickness ratio of ore and coke in the radial direction and the particle size of the charge, and this information is used to determine the optimal distribution in the radial direction. By moving the movable armor and rotating chute in such a way, it is possible to operate the blast furnace stably and improve its efficiency.

For example, in the radial center the ore to coke thickness ratio is high or the charge particle size is small. Or, if both of these occur simultaneously, the gas flow in the center is suppressed and reduction heat transfer is delayed, resulting in poor lowering of the charge due to the lowering of the cohesive zone and poor ventilation, which impedes stable operation. . Therefore, in order to promote gas flow in the center, stable operation can be maintained by reducing the amount of ore charged into the center by using a movable armor or rotating chute, and by reducing the amount of fine particles charged. be able to.

〔Example〕

FIG. 4 shows an embodiment of furnace circumferential balance control according to the present invention. In the figure, ○A is the time when the ore particle size decreases on the 90° side, and ○B is the time when an action is taken to reduce the layer thickness ratio of ore and coke on the 90° side. The insertion of the probe 5 is based on Figures 1a and 2, and the height H is 350 mm in the height direction from the surface of the charge.
The insertion depth L, which is the position inserted into the mm charge, is 350 mm from the brick operating surface. Among the sensor information mounted on the four probes, the layer thickness ratio of ore and coke is within the control range, but since the grain size of the charge on the 90° side has become smaller, the ore is not allowed to fall to this location by the rotating chute. The amount was reduced and the circumferential balance was resolved. The circumferential balance results are measured by the gas temperature near the wall at the top of the shaft, and it can be seen that the temperature is within the control range. In this example, the layer thickness ratio between the ore and coke was reduced at the location where the grain size of the charge became small, but if the blast furnace is charging ore by grain size, fine grains would be added to this location. You can also reduce the amount. FIG. 5 shows another aspect of the present invention in which the furnace is controlled in the radial direction. In the figure, ○A is the period when the grain size of the ore in the center decreased, and ○B is the period when an action was taken to reduce the layer thickness ratio between the ore and coke in the center. The insertion of the shaft sonde 5' is based on Figure 1b, the height H is at the periphery, 400 mm from the charge surface in the height direction into the charge, and the insertion depth L' is at the furnace core. up to 5500mm
It is. Among the sensor information in the center, the layer thickness ratio of ore and coke is within the control range, but because the particle size of the charge has become smaller, the amount of ore charged to the center has been reduced compared to movable armor. The flow was secured. The results are measured by the gas temperature at the center of the shaft sonde, which is within the control range.

〔Effect of the invention〕

As described above, operations that stably improve blast furnace efficiency by detecting the thickness ratio of ore and coke in the circumferential direction and the balance of particle size of the charge, and moving the movable armor and rotating chute to achieve the balance. became possible.

[Brief explanation of drawings]

FIG. 1a is a conceptual longitudinal cross-sectional view showing a probe inserted state according to the present invention, FIG. 1b is a vertical cross-sectional conceptual diagram showing a shaft sonde inserted state according to the present invention, and FIG. 2 is a conceptual longitudinal cross-sectional view showing a probe insertion state according to the present invention. FIG. 3a is a cross-sectional explanatory diagram of the probe used in the present invention, showing an example in which one probe is configured, FIG. 3b is another example in which two probes are configured in a set, and FIG. is an explanatory diagram of an embodiment of furnace circumferential balance control according to the present invention,
Fig. 5 is an explanatory diagram of an embodiment of furnace radial direction control according to the present invention, Figs. 6 and 7 are explanatory diagrams of a comparative example using the conventional method, and Figs. 8 and 9 are temporal changes in transmitted waves and reflected waves. FIG. DESCRIPTION OF SYMBOLS 1... Furnace wall, 2... Furnace core, 3... Charge, 5... Probe, 6... Microwave transceiver, 7... Signal processing device, 8... Transmission port, 9... Receiving port.

Claims (1)

[Claims] 1 The layer thickness ratio of ore and coke and the particle size of the charge at each measurement point are detected by a microwave sensor inserted at an appropriate position in the furnace circumferential direction or furnace radial direction within the charge at the mouth of the blast furnace. , a blast furnace operating method characterized by controlling the distribution of the charge based on the detected information.