JPS6224488B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Fields Providing a through hole in the converter wall to observe the inside of the furnace and inject necessary additives is an extremely effective method for operating a converter. The present invention relates to prevention of blockage of the furnace wall through-hole. Conventional technology The purpose of converter operation is to reduce the carbon contained in the molten metal using oxygen supplied during converter blowing, and to turn the slag-forming agent introduced into the furnace into sludge, thereby reducing the generated molten slag. The purpose is to cause dephosphorization, desulfurization, etc. to occur through the reaction between the molten metal and the molten metal. In this case, the slagging state of the slag is a major factor that determines the operational results.If the slag slag progresses excessively, it will promote the forming state of the slag and eventually cause an abnormal reaction in which the slag overflows outside the furnace, that is, slopping. Various problems arise, such as a decrease in work efficiency, a decrease in iron yield, a deterioration of the work environment, and damage to equipment. On the other hand, in the case of poor slag formation, the dephosphorization effect and the like deteriorate, making it impossible to obtain the desired quality. Therefore, it is necessary to adopt an operating method that does not cause slopping while allowing sufficient slag formation.
For this purpose, it is desirable to accurately grasp the situation inside the furnace from time to time and inject additives to promote or suppress slag formation as needed. In order to achieve the above objectives, the applicant has developed a device for observing light inside the converter furnace by providing a through hole in the converter wall.
60-228929) and a device for injecting a slopping suppressing material from a through hole (Japanese Patent Application Laid-Open No. 60-245715)
60-245716) was applied for a patent. In order for these devices to function effectively, it is necessary to prevent the through holes from being blocked, and a patent application has already been filed for a method for preventing blockage (Japanese Patent Laid-Open No. 60-228930) (Japanese Patent Laid-Open No. 60-234911). All of these methods mixed oxygen into the purge gas blown into the through holes. Problems to be Solved by the Invention Although the above-mentioned method of mixing oxygen into the purge gas is an extremely effective method, if the oxygen concentration is increased excessively, there is a risk that even the lining bricks will be melted and damaged. The gas in the furnace whose main component is carbon oxide is combusted, and the amount of recovered gas decreases, as well as its quality. The present invention provides an improved method of mixing oxygen into purge gas that minimizes these drawbacks. Means and Effects for Solving the Problems The structure of the present invention provides a method for preventing blockage of a through hole provided in the side wall of a converter for injecting additives and observing inside the furnace. A purge gas blowing device containing oxygen gas is attached to the probe and the photodetection end, and the oxygen concentration in the purge gas is changed depending on the state of slag forming detected by the photodetection end to prevent the through hole from being blocked. This is a method for preventing blockage of a through hole in a converter side wall. illustrating an example of an apparatus for carrying out the method of the invention,
The method of the present invention will be explained with the aid of figures. FIG. 1 is an explanatory diagram showing the entire outline of this method. In this figure, an additive injection probe having a built-in optical detection end for inside the furnace is illustrated as being installed in a through hole provided in the side wall of the converter. The additive injection probe 6, which is a part of the additive injection device in FIG. 1, has a built-in photodetection probe 62, which is a component of the photodetection device. As shown, a light detection end 61 is built in, and an observation window 63 is attached to the tip of the light detection end 61 by a chip 64. The photodetection end is made of a conductor, such as a quartz optical fiber, that transmits synchrotron radiation emitted from a high-temperature object with low loss, and a photoelectric conversion element 10 is coupled to the rear end via a connector 9. Furthermore, it is connected to an arithmetic device 11 and a determination device 12 . The slug forming detection situation in the present invention is obtained by a series of devices from the above-mentioned photodetection end 61 to the determination device 12, and its outline will be explained. During converter operation, slag formation inside the furnace progresses to some extent,
When the temperature of the gas above the slag becomes higher than the temperature of the slag, there is a clear difference in the wavelength and intensity relationship between the light emitted by the gas atmosphere and the light emitted by the slag. From this fact, we can understand the light inside the furnace and convert it into electricity, 3
Separates the species into wavelength ranges B (blue), G (green), and R (red), processes the image as area signals for each color in 8 colors, including black when no light is received, and calculates the size of the area for each color. and the magnitude of the change in area are respectively extracted as binary signals. Among these, the color or color combination that has the highest correlation with the slag forming state is determined from a large number of results, and from then on, a certain standard is set for that color or color combination, and the observed values are based on this standard. By comparison, it is possible to predict the situation inside the furnace, especially the possibility of slopping occurring. According to the inventor's experience, the above-mentioned highly correlated colors or combinations of colors are yellow; yellow and red; and yellow and white, and a sufficient determination success rate was obtained only with yellow colors. If the above explanation were to be expressed in a block diagram, it would be as shown in FIG. 2, which shows in more detail the portions grouped together as the arithmetic unit in FIG. 1. The image of the light inside the furnace captured by the photodetection end is input to the wavelength separation device 21 as a photoelectric conversion image signal by a photoelectric conversion element, for example, an ITV camera. Here, the entire wavelength range of the light inside the furnace is divided into B (blue), G (green), and R (red), which are extracted as video signals (R, G, and B signals) for each wavelength range, and are divided into appropriate thresholds. Binarization circuit 22 at the field level
It is binarized and input to the area calculation circuit 23. In the area calculation circuit, for example, in the case of a yellow area, the binarized R signal, the binarized G signal, and the binarized B signal are placed on a count pulse of 0.134 μsec, and R・Gon is calculated from the pulse between constant reset pulses x the binarized signal. , the number of Boff pulses is counted and output as a yellow area value. The area signal obtained in this way is divided into two systems, one system is binarized as it is by the binarization circuit 24 at an appropriate threshold level and input to the determination device, and the other system is the area signal. In order to extract the magnitude of the temporal change, the signal passes through a high-pass filter 25 and a positive value conversion circuit 26, is converted into a binary value by a binarization circuit 27, and is input to the determination device 12. The determination device uses a combination of these two binary signals to determine the possibility of slopping occurring, for example, as shown in Table 1, and depending on whether the possibility is non-existent, low, medium, or high, it will issue no alarm, primary alarm, or a primary alarm, respectively. Issues secondary and tertiary alarms.

[Table] However, in reality, it is also necessary to consider the operational status of the converter at the time of judgment. For example, in the early stages of blowing, the gas temperature inside the furnace is low, so the light inside the furnace is biased toward yellowish colors, and the input of ore, the addition of auxiliary materials, the amount of silicon in the hot metal, etc. are also factors that cause the light inside the furnace to change, so information on these is also necessary. be. These are collectively illustrated as blowing conditions 28. Observing the furnace condition in this way, and using the information obtained, for example, if it is necessary to increase the amount of slag, it is preferable to charge oxidizing materials such as iron sand powder, sintered ore powder, scale powder, ferromanganese ore powder, etc. If it is necessary to suppress slag forming, it is preferable to charge a ring agent containing a carbon source such as coke powder or coal powder. Among these additives, in order to charge the ring agent which is particularly effective in suppressing slopping and cause a rapid reaction, the particle size should be 5 mm or less, preferably 3 mm.
It has been found that it is extremely effective to form the powder into a powder of less than mm in size, transport it in an air stream using a carrier gas, and blow it into the furnace through a blowing nozzle. FIG. 1 shows an example in which the above-mentioned furnace observation and additive injection devices are installed in conjunction with each other. That is, when the determination device 12 issues a tertiary alarm according to the determination in Table 1, for example, the blow control device 13 is activated and the stop valve 31 is opened to supply inert gas from the inert gas source 30. In addition to pressurizing the powder feeding tank 70, the flow rate regulator 53 of the carrier gas piping system 50 and the outlet valve 71 of the powder feeding tank are adjusted to supply the necessary amount of additives together with the carrier gas from the additive inlet 68. It is designed to be fed into a blow nozzle 69. Here, the carrier gas is a gas that does not react with the aforementioned additives at room temperature, does not easily react with the contents of the furnace when blown into the furnace, and does not affect the target steel composition. is preferable, and an inert gas such as CO ₂ , Ar, or N ₂ is used. Since the additive injection nozzle and the photodetection end are installed in the through hole, their tips in particular are exposed to high temperatures and are likely to be worn out, so they must be cooled. It is also necessary to prevent dust from adhering to the observation window attached to the tip of the light detection end. To meet these needs, a certain amount of inert gas is usually blown. This gas is hereinafter referred to as purge gas,
The purge gas is divided into three systems and introduced. The purge gas piping system 41 is equipped with normal piping equipment such as a stop valve, a pressure reducing valve, a flow rate adjustment device, a stop valve, etc., and is led to a purge gas inlet 66, passes through a gap 65 in the photodetection probe 62, and cools the photodetection probe. The purge gas is discharged into the furnace through a purge gas outlet 67 provided in the chip 64 while preventing dust from adhering to the observation window 63. The purge gas piping system 42 is the purge gas piping system 4
1, the purge gas passes from the purge gas inlet 692 of the additive injection probe 6 through the gap 691 between the additive injection nozzle 69 and its outer cylinder, cools the injection nozzle and the outer cylinder, and enters the furnace. released. Another purge gas piping system is a carrier gas piping system 50 in which a fixed amount of inert gas is allowed to flow through the additive injection nozzle even when the additive is not being blown into the system. Although the photodetection probe and the additive injection nozzle are protected by the purge gas described above, the cooling effect of this purge gas actually accelerates the clogging of the through holes. The cause of through-hole blockage is the adhesion of the contents of the furnace to the through-hole during blowing, or the hanging of slag, etc. during past blowing.According to the inventor's experience, even if the purge gas is Even when the discharge speed at the outlet of the through hole was set to about 22 m/sec, the effect of increasing the speed was observed, but clogging could not be prevented. As a result of various studies regarding purge gas, we found that mixing oxygen into purge gas is effective in preventing blockages.
The fact that the O ₂ concentration in the mixed gas is preferably about 30 to 45% has already been disclosed in the above-mentioned patent by the applicant
−228930). To explain this using the examples shown in FIGS. 1 and 3, an O ₂ gas piping system 55 is connected to the purge gas piping system 42,
The O ₂ -containing gas is supplied to the additive injection probe from the purge gas inlet 692 and is configured to be ejected from the tip opening 693 . Therefore, the content of O ₂ in the purge gas piping system 4
Since the flow rates of 1 and 50 can be kept constant, the flow ratio of the flow rate regulator 58 of the purge gas piping system 42 and the flow rate regulator 57 of the O ₂ gas piping system is set by the ratio setting device 56, so that the amount of oxygen relative to the total purge gas amount is The amount added can be adjusted. In this example, the O ₂ -containing purge gas is ejected from the tip opening 693 of the outermost cavity 691 of the additive injection probe and is combusted at the tip, which effectively prevents the adhesion of slag and additives. ,
There is no damage to the light guide or observation window. However, the addition of O ₂ may damage the converter side wall bricks, and the
Since the gas, whose main component is CO, is combusted and its value is reduced, various studies were conducted to reduce the amount of O ₂ added to the necessary minimum. The results showed that blockage of the through hole can be prevented with an oxygen concentration of 10 to 15% when slag formation is normal, and that the forming state progresses and the above-mentioned primary, secondary, and tertiary alarms are transmitted. It has become clear that in some cases, this can be prevented by changing the oxygen concentration to suit each case. The oxygen concentration that should be changed increases as the number of alarms increases, and its absolute value varies depending on the judgment criteria, the position and dimensions of the furnace volume and through holes, etc., so it is difficult to make a general rule, but here is an example. will be shown in Examples below. Based on the above knowledge, as shown in FIG. 1, the present method can be implemented by inputting the judgment of the judgment device 12 for detecting a slug forming situation to the ratio control device 14 and controlling the ratio setting device 56. In the above explanation, an example was shown in which an additive injection nozzle and a light detection end were installed in one through hole, but the invention is not limited to this. This method can also be implemented even if the detection end is provided as a separate device. Example A through hole with a diameter of approximately 15 cm is provided in the side wall of the converter at a height of approximately 4 m from the bottom of the 170 t/CH top-bottom blowing converter.
Using the apparatus shown in Fig. 3 and Fig. 3, the number of times the through hole was blocked with respect to the number of tests was determined by changing the amount of purge gas and the amount of added oxygen gas for each of the above-mentioned alarm categories. The results are shown in Table 2. In this example, the oxygen gas concentration in the purge gas is 10 to 15% when no alarm is issued, 25 to 35% when the primary alarm is issued, and 45 to 55% when the secondary alarm is issued.
%, 55 to 65% when the tertiary alarm is issued, and a purge gas amount of approximately 200 to 300 Nm ³ /H.

【table】

[Table] Effects of the invention As described in detail above, if this method is applied when operating a converter with through-holes for inside observation and additive injection, which are extremely useful in the operation of the converter, provided in the side wall of the converter, Blockage of the through hole can be prevented without damaging the refractory lining inside the furnace and without degrading the quality of the furnace gas to be recovered. Therefore, it greatly contributes to the operational management of converters and to improving the recovery gas consumption rate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the entire process of this method, FIG. 2 is a block diagram of a photodetecting device, and FIG. 3 is a diagram showing an example of an additive injection probe. 6...Additive injection probe, 9...Connector,
10...Photoelectric conversion element, 11...Arithmetic device, 12
...Determination device, 13...Blowing control device, 14...
Ratio control device, 21... Wavelength separation device, 22...
... Binarization circuit, 23 ... Area calculation device, 24 ...
Binarization circuit, 25... High-pass transmission filter, 26
... Positive value conversion circuit, 27 ... Binarization circuit, 28 ...
Blowing conditions, 30... Inert gas source, 31... Stop valve, 41... Purge gas piping system, 42... Purge gas piping system, 50... Carrier gas piping system, 5
1... Stop valve, 52... Pressure reducing valve, 53... Flow rate adjustment device, 54... Stop valve, 55... O ₂ gas piping system,
56...Ratio setter, 57...Flow rate control valve, 58
...flow control valve, 61 ... light detection end, 62 ... light detection probe, 63 ... observation window, 64 ... chip, 65 ... gap, 66 ... purge gas inlet, 6
7...Purge gas outlet, 68...Additive inlet, 6
9...Additive injection nozzle, 691...Void, 69
2...Purge gas inlet, 693...Tip opening,
70...Powder feeding tank, 71...Outlet valve, 72...
receiving tank.

Claims (1)

[Claims] 1. A method for preventing blockage of a through hole for injecting additives and observing inside the furnace provided on the side wall of a converter, which includes an additive injecting probe installed in the through hole and a purge gas injecting device containing oxygen gas at the photodetection end. A method for preventing blockage of a converter side wall through-hole, the method further comprising: changing the oxygen concentration in the purge gas depending on the state of slag forming detected by the light detection end to prevent the through-hole from clogging.