JP6583204B2 - Slag height measuring device, slag height measuring method and hot metal pretreatment method - Google Patents

Description

  The present invention relates to a slag height measuring device, a slag height measuring method, and a hot metal pretreatment method for measuring the slag height in a refining vessel.

  In recent years, hot metal pretreatment technology has advanced, and various hot metal pretreatment methods using a converter-type refining furnace have been developed. For example, in Patent Document 1, when desiliconization, dephosphorization, and decarburization processes are performed using a converter, the molten iron of the next charge is charged into the converter without discharging the decharged slag of the previous charge. Then, when Si in the hot metal becomes 0.2% or less, at least a part of the slag (also referred to as “desiliconized slag” generated by the desiliconization process) is discharged, and then dephosphorization and decarburization processes are performed. A method is disclosed.

In the method described in Patent Document 1, from the viewpoint of processing time, processing cost, etc., a problem is how a sufficient amount of desiliconized slag can be discharged from the converter in a short time. In order to solve this problem, it is necessary to stably form the desiliconization slag in the converter during the desiliconization process. However, excessive forming may cause slumping during the desiliconization process or bumping during discharge. Invite the outflow. For this reason, there is a demand for a technique for controlling the forming amount of the desiliconized slag to an appropriate range using measurement data such as the slag height of the desiliconized slag.
For example, in Patent Document 2, before the dephosphorized hot metal is blown in the converter, the bath surface level in the converter is measured, and the set lance height is adjusted based on the measurement data and blown. A method for suppressing the occurrence of slopping or spitting by processing is disclosed.

In Patent Document 3, by measuring the slag height of desiliconized slag during desiliconization treatment in a converter type refining furnace using a microwave, and adjusting the processing conditions based on the measurement results, A method for controlling the amount of desiliconized slag forming has been proposed. In the method for measuring the slag height described in Patent Document 3, a microwave having a frequency of 10 GHz or less is transmitted into a converter type refining furnace using a pseudo-random signal processing radar type microwave rangefinder, and reflected from the inside of the furnace. The wave is received, and the distance to the object is obtained from the round-trip propagation time of the reflected wave. And, among the reflected wave signals from the object existing in the range from the furnace port to the hot metal bath surface, the distance to the object corresponding to the reflected wave signal does not change from the start of the desiliconization process, The reflected wave signal that exists continuously is removed as noise. Furthermore, except for the reflected wave signal corresponding to the hot metal bath surface, the reflected wave signal having the highest reflection intensity is determined as the reflected wave signal from the slag surface, and the distance to the slag surface is obtained. The slag height is measured based on the distance.
Further, in Patent Document 4, in the slag level measurement method using microwaves, an axis indicating the traveling direction of the microwaves, that is, a line connecting the center of the antenna and the center of the microwave irradiation range is a main lance or a rotation. It is disclosed that the antenna is installed so as to be inclined with respect to the furnace wall of the furnace.

Japanese Patent Laid-Open No. 11-323420 JP 2012-107304 A International Publication No. 2014/115526 JP2015-110817A

However, the method described in Patent Document 1 does not disclose a method for measuring or controlling the forming amount of desiliconized slag.
Moreover, in the method of patent document 2, a measuring object is the bath surface of the hot metal before a blowing process, and the method of measuring slag height and the amount of forming is not disclosed.
Furthermore, in the method described in Patent Document 3, most of the transmitted microwaves are scattered by the metal that adheres to the furnace mouth of the converter-type refining furnace or the furnace wall immediately below the furnace mouth, and the slag is scattered. It occurs that the reflected wave from the surface cannot be captured. In particular, as the number of times the converter type refining furnace is used, a large amount of metal is attached to the furnace port and the furnace wall and grows, making it difficult to accurately measure the slag height.

  Furthermore, in the method described in Patent Document 4, when the axis of the microwave is inclined, a corner reflection effect occurs at the main lance, the furnace wall, and the slag surface, resulting in a large reflected signal from the slag surface. Is expected. However, the slag surface is constantly moving under the influence of blowing oxygen blown from the bottom blowing gas or lance, and further, the slag surface rises by about 4 to 8 m as the blowing proceeds. For this reason, it has been difficult to move the inclination of the axis during blowing so that a corner reflection effect can be sufficiently obtained. In addition, the signal reflected from the lance body or the furnace port itself becomes a disturbance, and accurate measurement cannot be performed.

  Therefore, the present invention has been made paying attention to the above problems, and a slag height measuring device and a slag height capable of accurately measuring the slag height in a refining vessel such as a converter type refining furnace. The object is to provide a measuring method and a hot metal pretreatment method.

  According to one aspect of the present invention, there is provided a slag height measuring device that measures the slag height in a smelting vessel using a microwave, and transmitting and receiving the microwave, Measuring the height of the horizontal surface of the slag, calculating the slag height based on the measurement result, and having an opening surface cut obliquely with respect to the vertical direction at the lower end in the vertical direction, A horn-type receiving antenna used for microwave reception, and a horn-type transmitting antenna used for microwave transmission, having an opening surface perpendicular to the vertical direction at the lower end in the vertical direction, A slag height measuring device is provided.

  Moreover, according to one aspect of the present invention, there is provided a slag height measurement method for measuring the slag height in a refining vessel using a microwave, wherein the microwave is transmitted using a horn-type transmitting antenna. Transmitting and receiving the transmitted microwave using a horn-type receiving antenna, the height of the horizontal surface of the slag in the refining vessel is measured, and the measured height of the horizontal surface of the slag Based on the measurement results, the slag height is calculated, and the receiving antenna is formed with an opening face that is cut obliquely with respect to the vertical direction at the lower end, and the transmitting antenna is An slag height measuring method is provided, wherein an opening surface perpendicular to the vertical direction is formed at a lower end.

  Furthermore, according to one aspect of the present invention, the hot metal is desiliconized by blowing oxygen gas from the top blowing lance into the hot metal accommodated in the converter type refining furnace, and a part of the slag generated by the desiliconization process Is discharged from the converter-type refining furnace, and after a part of the slag is discharged, a CaO-based solvent is added to the converter-type refining furnace, and oxygen gas is blown from the top blowing lance. When dephosphorizing the hot metal inside and desiliconizing the slag, the slag height in the converter-type refining furnace is measured and the processing conditions are adjusted according to the measured slag height. When controlling slag and measuring the slag height, the above-described slag height measuring method is used, and a hot metal pretreatment method is provided.

  According to one embodiment of the present invention, the slag height in the smelting vessel can be measured with high accuracy.

It is a mimetic diagram showing a converter type refining furnace concerning one embodiment of the present invention. It is side surface sectional drawing of a slag height measuring apparatus. It is front sectional drawing of a slag height measuring apparatus. It is a three-plane figure which shows the antenna for transmission of a slag height measuring apparatus. It is a three-plane figure which shows the antenna for reception of a slag height measuring apparatus. (A) It is explanatory drawing which shows the directivity angle in the antenna of FIG. (B) It is explanatory drawing which shows the directivity angle in the antenna of FIG. It is a graph which shows intensity attenuation | damping in the antenna of FIG. It is a graph which shows the intensity attenuation | damping in the antenna of FIG. It is explanatory drawing which shows the irradiation area | region of the microwave in a furnace port position. It is a graph which shows the measurement result of the intensity | strength of the reflected wave in an Example.

  In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

<Configuration of slag height measuring device>
First, with reference to FIGS. 1-8, the structure of the slag height measuring apparatus 5 which concerns on one Embodiment of this invention is demonstrated. A converter type refining furnace 1 that is a refining vessel includes a furnace body 2, a hood 3, a main lance 4, and a slag height measuring device 5. 1 to 3, the z-axis direction is a vertical direction, and the x-axis direction is a horizontal direction orthogonal to the z-axis.
The furnace body 2 has a furnace port 21 as an opening at the top, and a refractory is provided on the entire inner wall. In addition, a plurality of bottom blowing tuyere connected to a gas supply device (not shown) is provided at the bottom of the furnace body 2. A stirring gas such as Ar or N ₂ that stirs the hot metal M is blown into the hot metal M from the bottom blowing tuyere.

  The hood 3 is provided on the upper side in the vertical direction, which is the positive z-axis direction side of the furnace body 2 so as to cover the furnace port 21, and is connected to an exhaust facility (not shown). In the hood 3, a main lance hole 31 into which the main lance 4 is inserted and a sub lance hole 32 into which the slag height measuring device 5 is inserted are formed immediately above the furnace port 21 on the z-axis positive direction side. The main lance hole 31 is a hole extending in the z-axis direction, and is provided at the center of the furnace body 2 in the xy plan view. The sub lance hole 32 is a hole extending in the z-axis direction, and is provided at a position shifted to the x-axis positive direction side from the main lance hole 31 in the xy plan view. The sublance hole 32 is a hole provided with a sublance for temperature measurement and sampling when the decarburization refining process is performed in the converter type refining furnace 1. However, in this embodiment, since the sublance is not used in the blowing process of the converter type refining furnace 1, the slag height measuring device 5 is provided in the sublance hole 32 instead of the sublance. As shown in FIGS. 2 and 3, the hood 3 around the sub lance hole 32 is composed of an inclined surface whose upper end is a horizontal plane parallel to the x-axis direction and whose lower end is positively inclined with respect to the x-axis. In the present embodiment, the upper end of the hood 3 around the sublance hole 32 is a deck such as a sublance facility.

The main lance 4 is an upper blowing lance extending in the z-axis direction, and is provided so as to be able to be raised and lowered in the z-axis direction through the main lance hole 31. The main lance 4 injects oxygen gas to the hot metal M accommodated in the furnace body 2 from the end on the z-axis negative direction side.
As shown in FIG. 1, the slag height measuring device 5 is provided on the z-axis positive direction side of the converter type refining furnace 1 and measures the slag height of the slag S in the furnace using microwaves. As shown in FIG. 2, the slag height measuring device 5 includes a measuring unit 51, a coaxial waveguide converter 52, a pair of waveguides 53a and 53b, a pair of antennas 54a and 54b, and a fixed portion. Part 55.

  The measurement unit 51 is a microwave radar distance meter having a signal generation circuit and a processing circuit, and is connected to the coaxial waveguide converter 52 by a cable. The measurement unit 51 performs transmission / reception of a microwave signal having a carrier frequency equal to or lower than the X band with the coaxial waveguide converter 52. Moreover, the measurement part 51 measures slag height using the method mentioned later based on the received microwave signal. The microwave carrier frequency is desirably as low as possible in consideration of dust permeability. However, if the carrier frequency is lowered, the antenna 54a is increased in size, and if the carrier frequency is too low, the beam convergence is lost. Therefore, the carrier frequency is set in consideration of these points. Furthermore, various methods including a method using a pseudo random signal, an FMCW method, and a UWB method can be applied to the measurement unit 51.

  The coaxial waveguide converter 52 is connected to the measurement unit 51 with a cable, and the waveguides 53a and 53b are connected to the lower ends. The coaxial waveguide converter 52 converts the signal transmitted from the measurement unit 51 into a microwave, and sends the converted microwave to the waveguide 53a. Further, the coaxial waveguide converter 52 converts the microwave transmitted from the waveguide 53 b into a signal, and transmits the converted signal to the measurement unit 51.

The waveguide 53a is a transmission waveguide, and the upper end extending in the z-axis direction is connected to the coaxial waveguide converter 52 and the lower end is connected to the antenna 54a. On the other hand, the waveguide 53b is a transmission waveguide, and the upper end extending in the z-axis direction is connected to the coaxial waveguide converter 52 and the lower end is connected to the antenna 54b. The pair of waveguides 53 a and 53 b are provided side by side in the y-axis direction, and the lower end portion is fixed to the fixing portion 55. Further, four N ₂ gas introduction pipes (not shown) are attached to the pair of waveguides 53a and 53b, and N ₂ gas is introduced as a purge gas. Note that the diameter of the N ₂ gas introduction tube is preferably shorter than the wavelength of the irradiated microwave. The purge gas prevents adhering to the inside of the antennas 54a and 54b, which is called splash, which is scattered during blowing. When splash adheres to the inside of the antennas 54a and 54b, the antennas 54a and 54b are blocked, and the propagation of microwaves is hindered.

  The antenna 54a is a square horn antenna for transmission that transmits microwaves. The antenna 54a is inserted into the sublance hole 32 with its upper end connected to the waveguide 53a, and is arranged to extend in the z-axis direction. The antenna 54a is preferably made of stainless steel because it needs to have heat resistance, but may be made of other metals having a high melting point. On the surface of the antenna 54a, a release agent for preventing adhesion of granule and iron particles is applied. As the release agent, BN (boron nitride) is suitably used as a release agent having no electrical conductivity and heat resistance. As shown in FIG. 4, the antenna 54a is formed so that the opening area on the lower end side gradually increases with respect to the upper end side. The antenna 54a has an opening surface in which a lower end 541a having a large opening area is orthogonal to the longitudinal direction.

  The antenna 54b is a receiving rectangular horn antenna that receives microwaves. The antenna 54b is arranged so as to be inserted into the sub lance hole 32 with its upper end connected to the waveguide 53b and to extend in the z-axis direction. The material of the antenna 54b is the same as that of the antenna 54a. Further, the antenna 54b has an opening surface that is obliquely cut so that a lower end 541b having a large opening area is inclined at a predetermined angle with respect to a surface orthogonal to the longitudinal direction (the z-axis direction which is the vertical direction). The lower end 541b is inclined obliquely so that the length in the longitudinal direction is longer than the positive direction of the x-axis. That is, the opening surface of the lower end 541 b is provided so as to face the center side of the furnace body 2. Further, as shown in FIG. 2, the pair of antennas 54a and 54b are provided side by side in the y-axis direction.

  Here, the microwave transmitted from the horn antenna has an irradiation range determined by the directivity characteristics of the antenna, and has a value that maximizes the gain with respect to the length L in the longitudinal direction and the opening angle α. The antenna 54a, which is a general square horn antenna, has an opening surface at the lower end perpendicular to the traveling direction of the microwave so that microwaves and electromagnetic waves travel straight, and the beam width is equal to that of the antenna opening surface. Contrast with the center. Further, the directivity of the horn antenna becomes sharper as the length L in the longitudinal direction is longer. Further, it is known that the beam width (directivity angle) θ of the horn antenna is represented by the following approximate expression (1) using the antenna width D and the microwave wavelength λ. According to the equation (1), it can be seen that the larger the opening area at the lower end of the antenna corresponding to the antenna width D, the sharper the directivity.

When the reflected wave from the furnace port 21 is captured, when an antenna having the same radiation pattern as the transmitting antenna is used as the receiving antenna, the reflected signal intensity from the furnace port 21 is large and sufficient S / N ratio may not be obtained.
Therefore, the inventor uses a transmission antenna 54a in which the opening surface of the lower end 541a is orthogonal to the main lance, and a receiving antenna in which the opening surface of the lower end 541b has an angle that is not perpendicular to the main lance. Thus, the inventors have conceived that the reflection signal from the furnace port 21 can be suppressed from being received.

  Up to now, for example, there has been a finding that the propagation direction of electromagnetic waves such as microwaves is deflected by obliquely cutting off the tip of a transmitting antenna like the antenna 54b shown in FIG. According to such an antenna, the area occupied by the furnace in the microwave irradiation range can be increased. The same applies to the receiving antenna, and the tip of the receiving antenna is cut off at an angle in the same manner as the transmitting antenna, so that it is reflected from the range corresponding to the irradiation area of the transmitting antenna. It is possible to efficiently receive incoming microwaves.

  However, the front end of the transmitting antenna is cut obliquely so that the transmitting antenna is deflected toward the center of the furnace port 21, and the front end of the receiving antenna is also cut obliquely. The reflection from the main lance 4 disposed at the center of the furnace port 21 may become noise. In other words, in order to avoid the influence of disturbance elements such as the main lance 4 existing around the slag S to be measured, it is necessary to limit the microwave irradiation region to the slag S as much as possible. However, when both the transmitting and receiving antennas have the same shape, if the microwave irradiated from the transmitting antenna hits the furnace port 21 or the main lance 4, the reflected signal has the same intensity distribution. Will be detected.

Therefore, the present inventor examines a combination of a transmission antenna and a reception antenna, and changes the tip shapes of the transmission antenna and the reception antenna like the antennas 54a and 54b of the present embodiment. As a result, it was found that the apparent microwave irradiation region could be narrowed down.
When the antenna 54b with a notch is used as a transmitting antenna, the irradiated microwave is centered on the x-axis direction center of the lower end 541b with respect to the y-axis, as shown in FIG. Irradiation is performed with a directivity angle of angle β on the x-axis positive direction side and angle γ on the x-axis negative direction side. In other words, the microwave irradiated from the antenna 54b has a beam width that is asymmetric with respect to the center of the opening surface because the opening surface of the antenna 54b is notched obliquely, and has a directivity angle on the negative side of the x axis. On the other hand, the directivity angle on the x-axis positive direction side is reduced, and irradiation is performed in the traveling direction toward the center of the furnace body 2.

  On the other hand, when the antenna 54a in which the opening surface of the lower end 541a is orthogonal to the longitudinal direction is used as a transmitting antenna, the irradiated microwaves are on the x-axis positive direction side as shown in FIG. The directivity angle δ is the same as the directivity angle δ on the x-axis negative direction side. For this reason, compared with the antenna 54b, the microwave irradiation range spreads to the x-axis positive direction side, and the area occupied by the furnace in the microwave irradiation range becomes smaller.

  This inventor investigated the intensity | strength and characteristic of the signal transmitted from an antenna using such an antenna of two types of shapes. In the investigation, microwaves were irradiated using the antennas 54a and 54b, and the intensity of the reflected waves was measured. As the antenna 54b with the tip cut out, an antenna 54b having a long side length L1 of 1.15 m and a short side length L2 of 0.85 m with respect to the longitudinal direction was used. As the antenna 54a in which the opening surface of the lower end 541a is orthogonal to the longitudinal direction, an antenna 54a having a length L in the longitudinal direction of 1.15 m is used. The maximum length (1.15 m) in the longitudinal direction of the antennas 54a and 54b is made to coincide with the average value of the lengths of the sublance holes 32. In the measurement, a microwave having a carrier frequency of 8.5 GHz was modulated with a 127-bit pseudorandom signal having a clock frequency of 800 MHz and transmitted as a transmission wave. The length of the notch provided on one side of the short side surface of the antenna 54b was 141.2 mm, which is four times the wavelength 35.3 mm corresponding to the carrier frequency of 8.5 GHz. And the signal reflected on the slag surface in the furnace was received. The received signal was detected by a signal processing circuit, and demodulated by mixing (multiplying) the pseudo random signal with a slightly different clock frequency of the transmitted signal.

  FIG. 7 and FIG. 8 show the propagation characteristics of the antenna 54b with the tip cut off and the antenna 54a whose opening surface is orthogonal to the longitudinal direction, respectively. As shown in FIG. 7, it can be seen that the signal propagation intensity is asymmetric in the antenna 54 b with the tip cut off. As for the horn antenna having such characteristics, when the antenna 54b having a notch at the tip is used for the reception and the antenna 54a whose opening surface of the lower end 541a is orthogonal to the longitudinal direction is used for the transmission, both A reflected signal is received from a region where the irradiation region and the reception region of the antennas 54a and 54b overlap. Furthermore, since the microwave irradiated to this area | region is irradiated to the inside (furnace) of the furnace body 2 of a converter, it becomes possible to measure a slag level accurately.

  FIG. 9 shows reception areas and irradiation areas of the antennas 54a and 54b of the present embodiment. In FIG. 9, a region d1 surrounded by a broken line is a reception region of the antenna 54b (corresponding to an irradiation region when used as a transmission antenna), a region d2 surrounded by a broken line is an irradiation region by the antenna 54a, and regions d1 and d2 A hatched area d3 where the two overlap each other is a measurement area. As shown in FIG. 9, the antenna 54b receives the microwave reflected from the region d1. At this time, the reception area only overlaps the main lance hole 31 and the end when viewed from the z-axis direction, and the microwave reflected from the main lance 4 is hardly received. In the antenna 54a, the region d2 is irradiated with microwaves. The region d2 is substantially inside the furnace port 21, and the furnace body 2 (also referred to as a furnace port metal) around the furnace port 21 is hardly included. For this reason, the antenna 54 b can irradiate the microwave substantially inside the furnace body 2. In other words, the microwaves transmitted and received by the antennas 54a and 54b are irradiated and reflected on the region d3, so that the influence of disturbance elements such as the furnace mouth metal piece, the metal base attached thereto, and the main lance 4 should be reduced. And the height of the slag S can be measured with high accuracy.

  The height in the z-axis direction of the lower ends 541a and 541b of the antennas 54a and 54b on the x-axis positive direction side is set to the same height as the lower surface of the sub-lance hole 32 at the x-axis positive direction end. The microwave irradiated from the antenna 54a propagates so as to spread. For this reason, when the height of the lower end 541a on the x-axis positive direction side of the antenna 54a is higher than the height of the lower surface of the sublance hole 32, the microwave irradiated from the antenna 54a is multiple-reflected by the sublance hole 32 and measured with high accuracy. You will not be able to. On the other hand, when the height of the lower end 541a on the x-axis positive direction side of the antenna 54a is lower than the height of the lower surface of the sub lance hole 32, the antenna 54a protrudes from the inner surface of the hood 3, and spitting generated during processing causes There is a possibility that wrinkles adhere to the tip of the antenna 54a. If wrinkles adhere to the tip of the antenna 54a, the propagation performance of the antenna 54a changes. In addition, the height in the z-axis direction of the lower end 541a of the antenna 54a on the x-axis negative direction side is higher than the height on the x-axis positive direction side, and the height at which reflection of microwaves on the inner surface of the sublance hole 32 is satisfactory. Is set. The same applies to the antenna 54b.

The antenna 54a is preferably provided so that the region where the signal strength decreases from the maximum strength at the center of the antenna 54a to a predetermined strength at the furnace port position does not overlap the main lance 4. Further, when the antenna 54b is used for transmission at the furnace opening position, the irradiation area (corresponding to the receiving area) in which the signal intensity decreases from the maximum intensity at the center of the antenna 54b to a predetermined intensity is the furnace mouthpiece. It is preferable to be provided so as not to overlap. The predetermined strength in the antennas 54a and 54b varies depending on the radiation characteristics of the antenna, but may be a value that decreases by 2 dB with respect to the maximum strength, for example. In the example shown in FIG. 9, areas d1 and d2 indicate irradiation areas (reception areas in the case of reception) from when the maximum intensity of the antennas 54a and 54b is reduced by 3 dB.
The fixing portion 55 is provided at the upper end of the hood 3 above the sub lance hole 32, and fixes the slag height measuring device 5 to the hood 3 by fixing the pair of waveguides 53 a and 53 b.

<Pretreatment method of hot metal>
Next, a preliminary treatment method for hot metal M according to this embodiment will be described. In the preliminary treatment according to the present embodiment, the converter type refining furnace 1 is used to continuously perform the desiliconization treatment and the dephosphorization treatment of the hot metal M. First, the hot metal M, the slag S generated by the pre-charge dephosphorization process, which will be described later, and the medium solvent added as necessary are accommodated in the furnace body 2 and a predetermined amount of oxygen gas is blown from the main lance 4. (Also referred to as “blowing”) hot metal M is desiliconized. At that time, using the method for measuring the slag height described later, the height of the horizontal surface of the slag S is measured, and the slag height that is the height from the bath surface of the hot metal M to the upper end of the slag S is measured. By calculating from the result, the forming state of the slag S is monitored. Here, the forming of the slag S is a phenomenon in which the molten slag S includes CO bubbles generated during the blowing process and apparently expands in volume. This slag forming is the basicity of the slag S and the operation specifications. Since the forming conditions change depending on the slag height, it is necessary to constantly monitor and measure the slag height during blowing.
Further, when the slag height is monitored, whether or not the forming state is good is determined based on whether or not the slag height is within the target range. That is, when the slag height is below the target range, it is determined that the slag S is not sufficiently formed, and when the slag height is above the target range, the slag S is excessive. It is judged that it is forming. Note that the target range of the slag height is set according to various conditions such as the amount of slag S generated by the dephosphorization treatment, the addition amount of the solvent, the component / treatment temperature of the hot metal M, and the blowing conditions.

  In the desiliconization process, if the slag S is not properly formed, a sufficient amount of the slag S cannot be discharged quickly and quickly in the exhaust process that is a subsequent process of the desiliconization process. For example, when the slag S is not sufficiently formed, the fluidity of the slag S is lowered, and the discharge rate of the slag S is reduced. For this reason, a sufficient amount of slag S cannot be discharged within a predetermined time. On the other hand, when the forming of the slag S becomes excessive, after the slag S is discharged from the furnace body 2 to the slag pot, the carbon in the granular iron discharged together with the slag S and the iron oxide in the slag S are discharged. Reacts and the forming proceeds further. When forming proceeds in the slag pot, there is a risk that the slag S overflows from the slag pot and hinders operation. For this reason, the discharge speed of the slag S must be reduced so that the slag S does not overflow from the slag pot, and the time required for the waste disposal process becomes long.

  Accordingly, when it is determined that the slag height is low and the forming is not sufficient, the supply flow rate and lance height of the oxygen gas from the main lance 4, the supply flow rate of the stirring gas, the addition of the solvent, etc. are performed. Thus, the adjustment is performed so as to obtain an appropriate slag height. On the other hand, when it is judged that the slag height is high and the forming is excessive, the slag height is adjusted by adding a forming sedative containing a gas generating substance such as C. Is done.

  After the desiliconization process is completed, an exhaust process for discharging a part of the slag S generated by the desiliconization process from the furnace body 2 is performed. In the waste disposal process, the furnace body 2 is tilted to discharge the slag S from the furnace port 21, and the discharged slag S is accommodated in a slag pot provided below the furnace body 2. At this time, from the viewpoint of the refining cost in the subsequent dephosphorization treatment and the productivity improvement in the converter type refining furnace 1, the waste treatment is performed so as to discharge a sufficient amount of slag S in a short time. Is required.

Next, after a predetermined amount of slag S is discharged, a CaO-based medium solvent is added to the furnace, and a predetermined amount of oxygen gas is blown from the top blowing lance to perform a dephosphorization process. After the dephosphorization process is completed, the hot metal M is discharged from a steel outlet (not shown) provided on the side of the furnace body 2 to the hot metal ladle. The hot metal M is discharged in a state where the slag S generated by the dephosphorization process is housed in the furnace body 2.
After the hot metal M is discharged, the hot metal M to be processed next is further stored in the furnace body 2 in which the slag S generated by the dephosphorization process is stored, and the above desiliconization process and dephosphorization process are repeated. Done.

<Measurement method of slag height>
Next, a method for measuring the slag height according to this embodiment will be described. In the present embodiment, the slag height of the slag S generated by the desiliconization process is measured. The slag height is measured over the entire duration of the desiliconization process.
First, the measurement unit 51 transmits a microwave signal to the coaxial waveguide converter 52 during the desiliconization process. The coaxial waveguide converter 52 converts the received signal into a microwave and irradiates the microwave through the waveguide 42a and the antenna 54a.

  Next, the coaxial waveguide converter 52 detects the reflected wave reflected from the metal body in the microwave irradiation region via the antenna 54b and the waveguide 53b, and uses the detected reflected wave as a reflected signal. It transmits to the measurement part 51. The measurement unit 51 measures the time (also referred to as propagation time) when the reflected wave is detected from the received reflected signal, and sets the value of ½ of the product of the propagation time and the propagation speed as the height of the horizontal surface of the slag S. calculate. In the present embodiment, the propagation speed is the speed of light. At this time, the reflected signal may include a part of the reflected wave from a metal body such as a furnace mouth metal around the furnace mouth 21 or a metal base attached thereto, but due to a difference in propagation time, A process of discriminating between the reflected signal and the reflected signal from the metal body such as the furnace port 21 and the metal may be performed. Since the metal body such as the furnace port 21 and the metal is located above the surface of the slag S, the propagation time is shortened. And the measurement part 51 calculates the slag height of the slag S by subtracting the height of the bath surface of the hot metal M calculated from the mass of the hot metal M from the height of the horizontal surface of the slag S.

<Modification>
Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. From the description of the invention, other embodiments of the invention will be apparent to persons skilled in the art, along with various variations of the disclosed embodiments. Therefore, it is to be understood that the claims encompass these modifications and embodiments that fall within the scope and spirit of the present invention.

For example, in the above embodiment, the pair of antennas 54a and 54b are square horn antennas, but the present invention is not limited to such an example. For example, the pair of antennas 54a and 54b may be round horn antennas. At this time, the lower end of the receiving round horn antenna is cut off obliquely in the same manner as the antenna 54b.
In the above embodiment, the pair of antennas 54a and 54b is provided inside the sub lance hole 32, but the present invention is not limited to such an example. A dedicated hole for providing the pair of antennas 54 a and 54 b may be formed at a position directly above the furnace port 21 of the hood 3. By setting it as the said structure, a sublance can be used during the blowing process in the converter type refining furnace 1. FIG. In addition, when the pair of antennas 54a and 54b is provided in the sublance hole 32, it can be applied to existing facilities, so that the investment cost of the facilities can be reduced.

  Furthermore, in the said embodiment, although it was set as the structure which performs the measurement of the height of the horizontal surface of slag S during the desiliconization process of the hot metal M, this invention is not limited to this example. The process of monitoring the forming of the slag S by measuring the height of the horizontal surface of the slag S and calculating the slag height may be performed at the time of dephosphorization of the hot metal M or at the time of decarburization. In any case, it is possible to prevent blowing failure due to insufficient forming of the slag S, occurrence of slopping due to excessive forming, extension of the evacuation time, and the like.

Furthermore, in the said embodiment, when calculating slag height, the height of the bath surface of the hot metal M calculated from the mass of the hot metal M was used, However, This invention is not limited to this example. For example, the height of the bath surface of the molten iron M is measured using the slag height measuring device 5 before the desiliconization treatment, and the measured height of the bath surface of the molten iron M is used when calculating the slag height. May be.
Furthermore, in the said embodiment, although the converter type refining furnace 1 was used, this invention is not limited to this example. For example, instead of the converter type refining furnace 1, other refining containers such as a topped type refining container may be used.
Further, in addition to the above embodiment, the lower end 541b of the antenna 54b may be cut out so that the perpendicular of the opening surface faces the center of the furnace body 2.

<Effect of embodiment>
(1) The slag height measuring device 5 according to one aspect of the present invention is a slag height measuring device 5 that measures the slag height in the refining vessel using microwaves, and transmits and receives microwaves. Thus, the height of the horizontal surface of the slag S in the smelting vessel (furnace body 2) is measured, and the measurement unit 51 that calculates the slag height based on the measurement result is cut obliquely with respect to the vertical direction. The lower end 541b in the vertical direction has a horn-shaped receiving antenna 54b used for microwave reception, and the lower end 541a in the vertical direction has an opening surface orthogonal to the vertical direction. And a horn-type transmitting antenna 54a used for transmission.

  According to the above configuration, by cutting the receiving antenna 54b obliquely, the ratio in the refining vessel can be increased as a measurement region where the receiving antenna 54b receives reflected waves. In this case, since the microwave irradiated from the transmitting antenna 54a is irradiated without being deflected, reflection from the main lance 4 can be suppressed. For this reason, the influence of disturbance elements can be suppressed, microwaves can be efficiently irradiated into the smelting vessel, and the reflected signal from the slag can be obtained with high intensity, so the slag height must be accurately measured. Can do. In addition, the slag height can be reliably measured regardless of the growth degree of the bullion attached to the furnace port 21 or the furnace wall of the smelting vessel (the shape that changes with each charge).

In addition, in the case of the method described in Patent Document 2, a large amount of dust is generated during the dephosphorization process, so that the reflection intensity is reduced by dust in addition to the reflection from the metal body. For this reason, it was difficult to measure the slag height during processing. On the other hand, according to the above configuration, since the ratio of the irradiation region in the smelting vessel is large, even when dust is generated, a reflection signal from the slag can be obtained with a higher reflection intensity than that of Patent Document 2, and therefore, the removal is eliminated. The slag height can be measured with high accuracy even during the phosphorus treatment.
Furthermore, in the configuration of (1) above, it is only necessary to cut off the lower end of the receiving antenna 54b obliquely, and therefore it is not necessary to provide the antenna itself with an inclination with respect to the vertical direction. For this reason, even when the installation place is narrow like the sub lance hole 32, it can be easily applied.

(2) The receiving antenna 54b is provided with an opening surface toward the substantial center of the smelting vessel.
According to the configuration of (2) above, microwaves can be irradiated more efficiently.
(3) The refining vessel is the converter-type refining furnace 1, and the transmitting antenna 54 a and the receiving antenna 54 b are provided in the sublance hole 32 of the converter-type refining furnace 1.
According to the configuration of (3) above, it can be applied to existing facilities at a low cost.
(4) The measurement unit 51 uses a microwave having a frequency equal to or lower than the X band.
According to the configuration of (4) above, the microwave dust permeability can be increased, and therefore the slag height can be measured with higher accuracy.

(5) A slag height measurement method for measuring the slag height in a refining vessel using a microwave, wherein the microwave is transmitted using a horn-type transmitting antenna 54a, and the transmitted microwave Is received using a horn-type receiving antenna 54b, the height of the horizontal surface of the slag S in the refining vessel is measured, and the slag is measured based on the measurement result of the height of the measured horizontal surface of the slag S. The height is calculated, and the receiving antenna 54b has an opening surface that is cut obliquely with respect to the vertical direction at the lower end 541b, and the transmitting antenna 54a has an opening surface that is orthogonal to the vertical direction. It is formed at the lower end 541a.
According to the configuration of (5) above, the same effect as (1) can be obtained.

(6) The hot metal M is desiliconized by blowing oxygen gas from the main lance 4 into the hot metal M accommodated in the converter type refining furnace 1, and a part of the slag S generated by the desiliconization process is converted into the converter type. After discharging from the refining furnace 1 and discharging a part of the slag S, a CaO-based solvent is added into the converter refining furnace 1 and oxygen gas is blown from the upper blowing lance, thereby converting the converter refining furnace. When dephosphorizing the hot metal M in 1 and desiliconizing, the slag height in the converter-type refining furnace 1 is measured and the processing conditions are adjusted according to the measured slag height. When the forming of the slag S is controlled and the slag height is measured, the slag height measuring method described in (5) is used.
According to the configuration of the above (6), since the forming of the slag S generated by the desiliconization process can be controlled to an optimum state, when the slag S is discharged, a sufficient amount of the slag S is reduced in a short time. Can be discharged. Thereby, the refining cost in subsequent dephosphorization processing can be reduced, and the productivity of the converter type refining furnace 1 can be improved.

  Examples performed by the present inventors will be described. In the examples, the slag height was measured using the slag height measuring device 5 according to the above embodiment. The shape of the antenna was the above survey. That is, in order to match the average length of the sublance holes 32, an antenna 54b having a long side length L1 of 1.15 m and a short side length L2 of 0.85 m in the longitudinal direction is used. The antenna 54a has a longitudinal length L of 1.15 m. Further, BN (boron nitride) was applied inside the antennas 54a and 54b.

  In the measurement, a microwave having a carrier frequency of 8.5 GHz was modulated with a 127-bit pseudorandom signal having a clock frequency of 800 MHz and transmitted as a transmission wave. The length of the notch provided on one side of the short side surface of the antenna 54b was 141.2 mm, which is four times the wavelength 35.3 mm corresponding to the carrier frequency of 8.5 GHz. And the signal reflected on the slag surface in the furnace was received. The received signal was detected by a signal processing circuit, and demodulated by mixing (multiplying) the pseudo random signal with a slightly different clock frequency of the transmitted signal.

  FIG. 10 shows the measurement result of the reflected wave. The horizontal axis in FIG. 10 indicates the distance from the antenna in the x-axis direction, and the vertical axis indicates the relative reflection intensity when the maximum value of the reflection intensity from the furnace port 21 is 1. As shown in FIG. 10, in the embodiment, the value of N (noise: reflected signal from the furnace port, reflected signal from the main lance) with respect to S (signal: reflected signal from the slag surface) can be reduced. It could be confirmed. For this reason, it was confirmed that the S / N ratio was large and the slag level could be measured with high accuracy.

  In addition, the temperature of the tips of the antennas 54a and 54b rose due to the radiant heat of the hot metal, but the sublance hole 32 was purged with room temperature gas, so that the temperature was almost room temperature above 300 mm from the tip, and thermal deformation was also observed. I couldn't. However, in the embodiment, in consideration of safety, it was made detachable at a position 600 mm from the tip. Furthermore, it was confirmed that by applying BN to the inside of the antenna, the amount of deposits at the tip was suppressed to a small amount, and stable measurement could be performed for a long time.

  As described above, in the slag height measuring apparatus according to the present invention, a part of the receiving horn antenna is cut out, so that the remaining surface becomes an electromagnetic wave shielding plate and diffuses to the furnace wall or the furnace port side. It was confirmed that electromagnetic waves can be reduced. As a result, it was possible to reduce reflection from the furnace wall or the furnace port, and it was confirmed that the slag height (level) can be measured with high accuracy. Moreover, according to this invention, even if it installed in a narrow through-hole, it has confirmed that it became possible to avoid reflection from a wall, without tilting an antenna. Furthermore, by making the tip part detachable, the maintainability is improved, and it can be confirmed that if the tip part is distorted due to adhesion of scattered melt or the like, it can be accurately measured if it is replaced.

DESCRIPTION OF SYMBOLS 1 Converter type refining furnace 2 Furnace body 21 Furnace 3 Hood 31 Main lance hole 32 Sub lance hole 4 Top blowing lance 5 Slag height measuring device 51 Measuring part 52 Coaxial waveguide converter 53a, 53b Waveguide 54a, 54b Antenna 541a, 541c Lower end 55 Fixed part M Hot metal S Slag

Claims (5)

A slag height measuring device for measuring the slag height in a refining vessel using a microwave,
By transmitting and receiving the microwave, to measure the height of the horizontal surface of the slag in the refining vessel, a measurement unit that calculates the slag height based on the measurement results;
A horn-shaped receiving antenna used for receiving microwaves, having an opening surface cut obliquely with respect to the vertical direction at the lower end in the vertical direction;
An opening surface perpendicular to the vertical direction at the lower end of the vertical direction, and a horn-type transmitting antenna used for transmitting the microwave , and
The antenna for receiving the all lower ends cut obliquely, slag height measuring device according to claim Rukoto provided perpendicular of the opening surface toward the sectional central axis of the refining vessel. The refining vessel is a converter type refining furnace,
The slag height measuring device according to claim 1, wherein the transmitting antenna and the receiving antenna are provided in a sublance hole of the converter refining furnace. The measuring unit, slag height measuring apparatus according to claim 1 or 2, characterized by using the microwave X-band frequencies below. A slag height measurement method for measuring the slag height in a refining vessel using a microwave,
By transmitting the microwave using a horn-type transmitting antenna and receiving the transmitted microwave using a horn-type receiving antenna, the height of the horizontal surface of the slag in the refining vessel Measure and
Based on the measurement result of the height of the measured horizontal surface of the slag, the slag height is calculated,
In the receiving antenna, an opening surface that is cut obliquely with respect to the vertical direction is formed at the lower end,
The transmission antenna is formed with an opening surface perpendicular to the vertical direction at the lower end ,
Antenna for the reception, all said lower end is cut obliquely, slag height measurement wherein the Rukoto provided perpendicular of the opening surface toward the sectional central axis of the refining vessel. Desiliconization of the hot metal by blowing oxygen gas from the top blowing lance into the hot metal accommodated in the converter type refining furnace,
A part of the slag generated by the desiliconization treatment is discharged from the converter type refining furnace,
After discharging a part of the slag, a CaO-based solvent is added into the converter type refining furnace, and oxygen gas is blown from the upper blowing lance to remove the molten iron in the converter type refining furnace. Phosphating,
When performing desiliconization treatment, the slag height in the converter type refining furnace is measured, and the forming of the slag is controlled by adjusting the processing conditions according to the measured slag height,
When measuring the slag height, the slag height measuring method according to claim 4 is used.

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