JP5674542B2 - Profile measurement method for blast furnace interior - Google Patents

Description

  The present invention relates to a method for measuring the shape (profile) of the surface of a blast furnace interior.

  In general, blast furnaces in the production of pig iron use blast furnaces alternately with sintered ore or lump iron ore (hereinafter simply referred to as iron ore or ore) and coke as the charge from the top of the furnace. The ore layer and the coke layer are formed in the furnace. The iron ore is heated and reduced (indirect reduction) by the CO gas generated by the reaction between the hot air blown from the tuyere below the blast furnace and coke, and part of the iron ore is reduced directly by the coke and softened and fused. After forming the band, it becomes a droplet. The droplets, that is, the molten iron, pass between the coke layers and accumulate at the bottom of the furnace. The ore layer and coke layer formed in the furnace gradually descend in the furnace, and the surface position of the charge at the top of the furnace inside the blast furnace fluctuates up and down.

  In the above process, it is very important to adjust the charge distribution at the top of the furnace formed by the iron ore and coke charged in the blast furnace to obtain an appropriate gas distribution. The profile (surface shape) of the charge at the top of the furnace in the blast furnace is determined by the moving armor in the bell-type charging device and the fall trajectory of the charge through the distribution chute in the bell-less charging device. Usually, the profile of the charge at the top of the furnace has a substantially inverted conical shape with a low center part around the center vertical direction (axial center) of the blast furnace. The profile of the blast furnace interior is important information for the operation of the blast furnace, and measuring devices and methods for measuring the profile of the charge charged and deposited in the furnace have been developed and put into practical use.

  For example, in Patent Document 1, a microwave probe provided with a microwave transmission / reception antenna and a transmission circuit is provided at a position outside the furnace top on the furnace center axis, and the microwave probe is rotated to transmit and receive microwaves. Thus, a measuring device for measuring the surface contour of the charge in the furnace is disclosed.

  Further, for example, in Patent Document 2, a sonde tube having a microwave transmission / reception function is inserted from the side surface of the furnace body toward the blast furnace axis, and the microwave is transmitted toward the blast furnace interior, A method for measuring the distance to the surface of the blast furnace interior is disclosed.

  When using these measuring devices, microwaves are scanned into the furnace, and the profile of the charge at each position in the furnace is sequentially measured. For this reason, a difference occurs in the measurement time between the measurement start position and the measurement end position, and the blast furnace interior falls during that time. Therefore, an accurate profile cannot be obtained unless the measurement value is corrected according to the measurement time difference.

  Therefore, a method for correcting the distance measurement data based on the descending speed of the charge measured in advance at an arbitrary position can be considered. However, the descending speed of the blast furnace interior varies depending on the position in the furnace, the center is small, and depending on the shape of the furnace, there is a difference of about 30% between the center and the vicinity of the furnace wall. Therefore, an accurate profile cannot be obtained unless correction according to the position in the furnace inner diameter direction is performed.

  As a method for removing the measurement error due to the descending of the charged material, Patent Document 3 discloses a method for detecting the profile of the charged material based on the average depth value of the forward path and the backward path measured at a constant speed.

Japanese Patent No. 2870346 JP 2002-275516 A Japanese Examined Patent Publication No. 4-37124

  However, as described above, since the descending speed of the blast furnace interior varies depending on the position in the furnace, in the case of Patent Document 3, the obtained estimated profile is not an accurate charging profile as shown in FIG. There's a problem.

  An object of the present invention is to provide a method for measuring a profile of a blast furnace interior, which can perform a highly accurate profile measurement in consideration of a descending amount of the charge depending on a position in the furnace.

  In order to solve the above problem, the present invention is a measurement method for measuring the surface shape of the furnace top of the blast furnace interior, and the surface of the furnace top of the blast furnace interior is diametrically passing through the central axis in the furnace. The depth of the same is measured multiple times with the same speed pattern in the same direction, and from the difference between the measured values multiple times, the charge lowering speed for each position in the diameter direction in the furnace is obtained, and the charging for each position is performed. Based on the object descent speed and the time difference from the start of measurement until the first measurement at each position, the amount of charge fall due to the time difference is calculated as a correction amount, and the correction is made to the first measurement value at each position. Provided is a method for measuring a profile of a blast furnace interior charge, wherein the profile of the charge at the start of measurement is estimated by adding and correcting the amount.

  In the method for measuring the profile of the blast furnace interior, the measurement point of the measuring device for measuring the surface of the top of the blast furnace interior passes through the central axis in the furnace. It is preferable to perform two reciprocating scans in the diametrical direction, adopt measurement data in the forward path as measurement values, do not adopt measurement data in the return path, or perform measurement in the return path, and scan the return path at a higher speed than the forward path.

  According to the present invention, the profile of the blast furnace interior can be measured with high accuracy in consideration of the descending amount of the charge depending on the position in the furnace. Therefore, it is possible to accurately grasp the change in the profile of the charge surface, to prevent the deterioration of the furnace condition of the blast furnace, and to stabilize the operation of the blast furnace.

It is a longitudinal cross-sectional view which shows the blast furnace top part provided with an example of the measuring apparatus which implements this invention. It is an enlarged side view which shows the structure of the measuring apparatus of FIG. It is explanatory drawing of embodiment of this invention, (a) shows the measured value and correction value of a charge profile, (b) shows the descent speed of the charge by each position of a furnace inner diameter direction, (C) shows the correction amount at each position in the furnace inner diameter direction. It is a longitudinal cross-sectional view which shows the blast furnace top part provided with the different example of the measuring apparatus which implements this invention. It is explanatory drawing of the conventional profile detection method of a charge.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows an example in which a profile measuring apparatus 1 for carrying out the measuring method of the present invention is installed in a blast furnace 2. A bell-less charging device 5 is provided at the furnace port portion of the blast furnace 2, and a charge 4 such as iron ore or coke is charged into the furnace through a distribution chute 6 that can turn in the furnace circumferential direction. . In the present embodiment, the profile measuring device 1 is installed at one place near the top of the furnace and outside the furnace body 3. A plurality of profile measuring devices 1 may be provided outside the top of the blast furnace 2.

  FIG. 2 is a diagram showing the internal structure of the profile measuring device 1. The measuring device 1 includes an antenna 11 and a reflecting plate 12, and a waveguide 13 that supports, drives, and controls the antenna 11 and the reflecting plate 12. A microwave transceiver 14, a drive shaft 15, and a reflector driving device 16 are included.

  The antenna 11 is a parabolic antenna having a diameter of about φ250 to φ360 mm, for example, and is connected to the microwave transceiver 14 via the waveguide 13. The microwave transmitter / receiver 14 generates a microwave whose frequency continuously changes in a certain range, and can transmit and receive the microwave. A data processor 20 is connected to the microwave transceiver 14 by a signal line.

  The microwave generated by the microwave transmitter / receiver 14 and continuously changing in frequency is radiated from the antenna 11 through the reflector 12 toward the measurement object, and the microwave (reflected wave) reflected by the measurement object is converted into the microwave. It is received and detected by the wave transceiver 14. In the data processing unit 20, the round-trip time ΔT of the microwave from the antenna 11 to the measurement target (the charge surface) is obtained from the change ΔF in the frequency from the emission to the reception of the microwave at the antenna 11. A distance from the antenna 11 to the measurement target is calculated. This measurement is based on the FMCW (Frequency Modulated Continuous Wave) method (Frequency Modulated Continuous Wave method) that mixes and measures the electrical signal that emits the microwave and the electrical signal that is obtained by receiving the reflected wave from the charged surface. ). A commercially available apparatus may be used for the microwave distance meter of this type. Such a distance measurement method using microwaves is an example that can be used as an embodiment.

  The transmission frequency band of the microwave used for measurement is 10 GHz or more, preferably about 24 GHz. The higher the frequency, the smaller the antenna 11 can be made. By using the microwave, the profile in the blast furnace 2 can be accurately measured without being affected by the environment such as temperature and dust. Moreover, since the parabolic antenna has high directivity, microwaves can be radiated to a desired position with high accuracy. Furthermore, since the spread of the microwave at the time of radiation | emission is suppressed, since the opening toward the inside of a furnace can be made small, it is preferable.

  A drive shaft 15 that connects the reflector 12 and the reflector driving device 16 is provided on an extension of the microwave transmission / reception direction (center axis direction) of the antenna 11. That is, the drive shaft 15 is provided so that the center axis of the drive shaft 15 coincides with the center axis of the antenna 11. As shown in FIG. 2, the reflector 12 is fixed to the drive shaft 15 at an angle of approximately 45 ° with respect to the central axis of the antenna 11. The reflector 12 is made of, for example, a stainless steel plate, and the area viewed from the front side of the antenna 11 is slightly larger than the antenna 11. Although the shape is not limited, a circular shape is preferable in terms of operability. By rotating and reciprocating the drive shaft 15 around its central axis by the reflector driving device 16, the microwave radiated from the antenna 11 in the central axis direction is reflected by the reflector 12 as shown in FIG. , Reflected toward the inside of the blast furnace 2 and scanned in the diameter direction passing through the central axis of the blast furnace 2.

  The profile measuring apparatus 1 as described above is housed in the pressure vessel 10 in order to prevent the gas, dust and the like inside the blast furnace 2 from leaking to the outside. Further, in order to prevent gas and dust inside the blast furnace 2 from entering the pressure vessel 10, nitrogen gas is introduced into the pressure vessel 10 so that the pressure is, for example, about 1.1 times the furnace pressure during measurement. It is preferable to supply the pressure vessel 10 so that the inside of the pressure vessel 10 has a positive pressure compared to the inside of the blast furnace.

  Hereinafter, a method for measuring a profile of a blast furnace interior according to the present invention using the profile measuring device 1 will be described with reference to FIG.

  First, the microwave is transmitted from the microwave transmitter / receiver 14 with the direction of the reflector 12 of the profile measuring device 1 directed to the initial position. The microwave is reflected by the reflecting plate 12 via the waveguide 13 and the antenna 11 and irradiated to the blast furnace interior entrance 4, and the distance D to the charge 4 is measured. The distance from the initial position at which the reflector 12 measures the distance to the charge in contact with the furnace wall directly below, to the charge in contact with the furnace wall on the opposite side in the inner diameter direction through the center axis of the furnace. Is rotated by the reflector driving device 16 until the position to measure is measured. The distance to the charge 4 is measured for each angle set in advance according to the desired spatial resolution, and the distance data is measured. The reflector driving device 16 has the scanning angle data at that time as the data processing unit 20. Sent to. This outward measurement is performed, for example, at an equal angular velocity over 50 seconds. In the return path, for example, the reflector 12 is rotated at a high speed so as to return to the initial position in about 5 seconds. Then, at a predetermined time interval such as 1 minute from the first measurement, the reflector 12 is rotated at the same speed as the first measurement, and the second outbound measurement is performed. The data processing unit 20 calculates the charge profile at each position in the blast furnace based on the input scanning angle data and the distance data at that time, and as shown by the broken line in FIG. And a second measurement profile is determined.

At this time, at each position in the inner diameter direction of the furnace, from the distance data Di (ta) at the first measurement time ta and the distance data Di (tb) at the second measurement time tb, The descending speed Vi of the entry 4 is calculated. The descent speed Vi at each position between the first measurement and the second measurement is obtained by the following equation (1).
Vi = (Di (ta) −Di (tb)) / (tb−ta) (1)

  Due to the influence of the furnace shape and the like, the descending speed Vi usually tends to increase toward the furnace wall, as shown in FIG.

Next, a correction value of the measured distance data is obtained. The amount of descent (correction amount di) of the time is obtained from the descent speed Vi of each position obtained by the above equation (1) and the time difference from the start of measurement until the first measurement at each position. The amount of descent for each position is added to the actually measured value of the first distance data. This estimates the charge profile at the start of measurement. That is, first, for each measurement position, the correction amount di is obtained by the product of the elapsed time ta from the measurement start time at which the initial position is measured and the descent speed Vi obtained by the above equation (1). As shown in FIG. 3C, the correction amount di is 0 at the initial position, and increases toward the opposite furnace wall. Then, as shown in FIG. 3A, the correction amount di is added to the actually measured value Di (ta) of the first distance data, and the distance Di (0) of each position indicating the profile at the start of measurement is obtained. That is, the corrected distance Di (0) is obtained by the following equation (2).
Di (0) = Di (ta) + Vi × ta (2)

  According to this embodiment, since the first and second measurement time intervals are all equal at each position in the inner diameter direction of the furnace, the descent speed Vi at each position can be easily calculated. Since the descent speed Vi at each position is obtained using measured values in the same direction, the descent speed Vi is not easily affected by the mechanical play of the scanning drive device.

  In this embodiment, when the reflector is reciprocated in the inner diameter direction of the furnace, distance measurement may be performed for both the forward path and the backward path, and only the distance data of the forward path may be employed during data processing, or the distance measurement may be performed only for the forward path. You may do it. In addition, by making the forward path low, a lot of measurement data can be acquired, and if the backward path is made high speed, waste of time can be reduced.

  In the present invention, the forward and return speeds may be equal. In this case, the measurement speed of the measuring device, for example, the profile measuring device 1 of FIG. 2, can be measured while keeping the rotational speed of the reflector 12 constant. Table 1 compares the measurement accuracy and measurement time by the profile measurement method. Conventional Example 1 is a method of the above-mentioned Patent Document 3, and Conventional Example 2 is a method of measuring a descending speed at an arbitrary point by reciprocating a microwave, and correcting outgoing measurement data based on the descending speed. . Example 1 of the present invention is a case where the speeds of the forward path and the return path are made equal in the above embodiment, and Example 2 of the present invention is a case where the return path is made faster than the forward path.

  As shown in Table 1, the accuracy in Conventional Example 1 is low, and the accuracy in Conventional Example 2 is higher than that in Conventional Example 1, but sufficient accuracy cannot be obtained. On the other hand, the first example of the present invention takes 1.5 times the measurement time of the conventional example, but a high-accuracy result is obtained. It is done.

  In the above-described embodiment, the forward path measurement is performed at an equal angular velocity. However, the angular velocity may vary as long as the first and second measurements are performed with the same angular velocity pattern. Moreover, you may obtain | require the charge fall speed | velocity | rate for every position by performing an outward measurement 3 times or more.

  In the above-described embodiment, the entire measurement in the diametrical direction in the furnace is performed from one furnace wall to the opposite furnace wall by the profile measuring device, but the charge is symmetric with respect to the central axis. As a result, only half of the diametrical direction may be measured to estimate the overall profile.

  The profile measuring apparatus used in the present invention is not limited to the one shown in FIG. 2, but may have a structure in which a microwave is scanned into the furnace by rotating a horn-shaped antenna that radiates microwaves, for example. Further, as shown in FIG. 4, a measurement lance 9 having a microwave distance meter is inserted from the side surface of the furnace body 3 toward the axis of the furnace body 3, and the microwave is directed toward the blast furnace interior entrance 4. It may be a measuring device that transmits and measures the distance to the surface of the blast furnace interior entrance 4. In addition, the measurement can be performed in the same manner with a measuring apparatus of a type that is conventionally used for measuring the profile of the blast furnace interior, and that scans the surface of the charge or measures at a plurality of measurement points.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to. For example, in the above embodiment, the measurement is performed twice when determining the descending speed of the blast furnace interior entry, but it may be performed three or more times.

  The present invention can be applied to the measurement of the surface shape of a deposit that increases and decreases over time in a cylindrical container.

DESCRIPTION OF SYMBOLS 1 Profile measuring apparatus 2 Blast furnace 3 Furnace body 4 Charge 5 Bell-less type charging apparatus 6 Distribution chute 10 Pressure | voltage resistant container 11 Antenna 12 Reflector 13 Waveguide 14 Microwave transmitter / receiver 15 Drive shaft 16 Reflector drive 20 Data processing Part

Claims (2)

A measuring method for measuring the surface shape of the furnace top of the blast furnace interior,
In the diametrical direction passing through the central axis in the furnace, the depth of the surface of the top of the blast furnace interior is measured several times with the same speed pattern in the same direction,
From the difference between the measured values of the plurality of times, find the charge drop speed for each position in the diameter direction in the furnace,
From the time of charge drop for each position and the time difference from the start of measurement until the first measurement of each position, the amount of charge drop due to the time difference is calculated and used as a correction amount,
A method for measuring a profile of a blast furnace interior charge, wherein the profile of the charge at the start of measurement is estimated by adding the correction amount to the first measurement value at each position to perform correction.   The measurement device for measuring the surface of the furnace top of the blast furnace interior contains two reciprocating scans of the measurement point on the surface of the furnace top of the blast furnace interior in the diametrical direction passing through the central axis of the furnace. The blast furnace interior entrance according to claim 1, wherein the measured value of the return path is not used, the measurement data of the return path is not used, or the measurement is not performed on the return path, and the return path is scanned at a higher speed than the forward path. Profile measurement method.

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