JPS5983708A - Method and apparatus for measuring material to be charged in shaft furnace - Google Patents

Abstract

PURPOSE:To make it possible to measure the falling speed, the layer thickness and the particle size of a material to be charged, by a method wherein an electric wave is radiated to a material to be charged into a shaft furnace and the pervious wave and the reflecte wave thereof are received. CONSTITUTION:A probe 1 is attached to a shaft furnace wall 18 where microwaves each having a wavelength near to the particle size of a material to be charged are outputted from an oscillator. The outputs thereof are alternatively radiated at a speed sufficiently higher than the falling speed of the material to be charged from the opening 21 of a waveguide 31 and the opening 22 of a wave guide 32 through an electric wave transmission and reception circuit 7. The radiated electric waves are reflected from the surface of material to be charged and received at respective openings 21, 22. In addition, pervious waves are transmitted from one opening and received from the outer opening. In this case, the falling speed of the material to be charged is measured from the delay times of direct reflected waves at the openings 21, 22 and the particle size thereof is measured from the fine variation thereof. In addition, the layer thicknesses of a coke layer and an ore layer are measured by the pervious waves.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring a blast furnace charge, such as a descending rate, a layer thickness, and a grain size.

In improving blast furnace operating technology, it is important to know the rate of descent of the charge, the thickness of the charge layer, the grain size, etc.

In recent blast furnace operation methods, it has become clear that the gas flow distribution is controlled by the layer thickness of ore and coke, the layer thickness distribution in the radial direction of the furnace, the particle size distribution, and the mixing state of ore and coke. The charging distribution control technology has been improved based on knowledge, and the development of technology to reduce blast furnace operating efficiency, that is, fuel ratio, has become desirable. This technology improvement requires the development of a sensing tip that can directly detect the charge.

The present inventor has confirmed that it is possible to radiate radio waves to the charge in the blast furnace and measure the state of the charge by combining transmitted waves and reflected waves for such purposes. That is, the present invention focuses on the radio wave propagation characteristics of the blast furnace charge, and the rate of descent of the charge is determined by the two-layer thickness.

It relates to a method and device for measuring particle size, etc., and its purpose is to detect the condition of the contents in the furnace.

If the wavelength of the radio wave is chosen to be relatively close to the particle size of the charge, and this radio wave is emitted onto the surface of the charge, and the transmitted radio waves are measured separately from the radio waves directly reflected from the surface, the power of the transmitted radio wave can be calculated. It was found that the attenuation is relatively small within the coke layer, and the attenuation is large within the ore. Therefore, by measuring the transmitted power, it is possible to distinguish between coke and ore. Further, the intensity of the radio waves reflected from the surface of the charge mainly changes depending on the geometrical shape on the order of the wavelength of the radio waves, that is, the unevenness. Therefore, by selecting the wavelength of the radio waves to be close to the average particle size of the charge and scanning the radio waves, or by moving the charge at a constant speed, changes in the intensity of the radio waves corresponding to the particle size can be obtained. Therefore, in order to measure the descending speed, layer thickness, and grain size of the charge, two probes equipped with radio wave transmitting and receiving functions are installed at different heights in the furnace using the above principle. If the above-mentioned transmission signal is detected by the probe and the falling speed is measured based on the signal, the layer thickness 9 grain size can be determined using this value.

The present invention is based on such a principle, in which two radio wave openings are installed in the blast furnace close to each other in the descending direction of the blast furnace charge, and radio waves are transmitted from one of the openings in tandem at a rate faster than the descending speed of the charge. Alternatively, radio waves are transmitted into the furnace alternately from two openings, and the falling speed, layer thickness, particle size, etc. of the blast furnace charge can be determined from the radio waves directly reflected from the opening and the radio waves received through the charge. The present invention relates to a method for measuring blast furnace charge and an apparatus therefor. The present invention will be explained below with reference to the drawings.

FIG. 1 is a longitudinal sectional side view of a probe used in the present invention, and FIG. 2 is a front view thereof. Reference numeral 1 denotes a probe attached to the blast furnace wall 18, and 21+22 denotes an opening into the sulin 1 provided in two stages, upper and lower, at the tip of the probe. Furthermore, this Surin 1
As shown in FIG. 2, the ~-shaped opening 21+''2 is made such that its long side is perpendicular to the direction of descent of the charge.The dimensions of this opening are, for example, 5 x 22.9 mm,
The distance between the openings 31 and 32 is 100 mm. 31,3□
are waveguides connected to apertures 21 + 22, respectively, 4++ 42
5 is a blowing port for blowing purge gas into the waveguides 31+32, and 5 is a waveguide 2. ．． 2. A cooling medium supply D for cooling the outer periphery of the
This is a radio wave transmitting/receiving circuit connected to the outer end of the

FIG. 3 shows this radio wave transmitting/receiving circuit, which includes a directional coupler 81182, a heterodyne detector 91°92, IF amplifiers 1.01, 102, . switch] Ij+112-output end 121, 122. switching signal generator 13, oscillator 14,
Coaxial switch 15, coaxial waveguide converter 1.6. ,1.6
2. It is composed of isolators 171+172, etc.

Note that these operations will be described later.

Moreover, FIG. 4 is an explanatory diagram showing a longitudinal section of the blast furnace, and 19
20 is the charged coke layer, 20 is the ore (sintered) layer, 21
2 is a cohesive zone, 22 is a tuyere, 23 is a taphole, and 24 is a furnace bottom.

According to the present invention, in order to measure the descending rate, layer thickness, particle size, etc. of the blast furnace charge, a probe 1 as shown in FIGS. 1 to 3 is attached to the blast furnace wall 18. Therefore, from the oscillator 14
When the band microwave is output, the output is guided to the openings 21 and 22 via the coaxial switch 15 and the coaxial waveguide converters 161 and 162. Therefore, for example, when the coaxial switch 15 is switched so that the output of the oscillator 14 (for example, +20 dBm) is coupled to the coaxial waveguide converter 16, the output of the oscillator 4 passes through the above path and is transmitted from the opening 121 into the furnace. radiated. The radio waves radiated into the furnace are reflected on the surface of the charge, enter the waveguide 31 through the opening 21, and enter the directional coupler 8.
1, heterodyne detector 91, IF amplifier 101. It is detected from the output end 121 via the switch 111. In addition, the radio waves radiated and transmitted into the charged material reach the waveguide 32 from the opening 22, and are passed through the directional coupler 82 and the heterodyne detector 9.
2. Output terminal 1 via IF amplifier 102 and switch 112
Detected from 22.

Furthermore, when the coaxial switch 15 is switched so that the output of the oscillator 14 is coupled to the coaxial waveguide converter 162, the aperture 22
Radio waves are radiated into the furnace from
Detected from 21.

Therefore, in the circuit configuration shown in FIG. 3, when the switching signal generator 13 generates a switching signal at a cycle sufficiently faster than the variation cycle of the measurement signal and the coaxial switch 15 is switched, the radio waves are transmitted to the aperture 2.
1 and 22 alternately. As a result, the output end 12. A directly reflected wave and a transmitted wave appear alternately in synchronization with the switching period, and a transmitted wave and a directly reflected wave alternately appear at the output terminal I22 in the form of a pair. Note that the output signal is output from switch 11. ,．． At step 112, the signal is separated into a directly reflected wave and a transmitted wave.

The opening 21 is located above the opening 22 (for example, 10° as described above).
0 mm), in the two measurement signals, the signal of the aperture 22 appears later than the signal of the gap L121 in terms of directly reflected waves, but there is no noticeable difference in the transmitted waves. The reason is that the directly reflected wave measures charge information just before the opening, but
This is because the transmitted wave measures the average information of the charge between the openings 21 and 22. Therefore, opening 2. ．． If the delay time of the directly reflected wave 22 is known, the descending speed of the charge can be found.

Here, the directly reflected wave and transmitted wave in the present invention will be explained. The contents in the blast furnace have a layered structure of coke and ore, as shown in Figure 4. Layer thickness is 20-5.0cm
The average particle size of coke is 50 mm, and the average particle size of sintered ore is 10 to 15 mm. As mentioned above, the wavelength of the radio waves used for measurement is closer to the average grain size of the charge, since the measurement can be made with better sensitivity, so we used microwaves in the X band (3 cm wavelength) and the probe It was attached to the furnace belly, and the tip of the probe protruded 50 cm into the furnace from the furnace wall.

Figure 5 shows the directly reflected wave and transmitted wave measured by the method of the present invention. First, when looking at the transmitted wave, we find that the coke layer has a gain of about -40 dBm, while the ore layer has a gain of -85 dBm. ]m. Therefore, the coke layer and the ore layer can be clearly distinguished from this gain difference. Also, the directly reflected wave is −
The level is finely varied from 10 to -20 dB+n.

This variation corresponds to the grain size of the charge; the maximum peak appears when ore or coke is present in front of the opening, and the minimum peak appears when there is a gap between ore or coke particles in front of the opening. Appears when the is located.

Next, open r12 from the direct reflected wave of output end 1.211122.
FIG. 7 shows a block diagram of a circuit that calculates the division of the delay time due to the descent of the charge by 1+22, the descent speed, and the grain size of the charge layer thickness. Direct reflected wave signal r 1 (1;) from output end 121 and direct reflected wave signal r from output end 122
2(t) has a similar waveform, and r2(t:) is slightly delayed. Therefore, in the following equation, ro is set to be sufficiently larger than the time required for the charge to pass between the openings 21 and 22. Generally, it will take about 15-20 minutes.

When ρ(τ) is calculated, a peak appears as shown in FIG. 8, and this time becomes the transit time T between the openings 21 and 22. Therefore, if the interval between the openings 21+27 is L, then the descending speed V is v=L/T---(2). The maximum value of r1(t) or r2(t) is the aperture 2+
This indicates that there is a charge agglomerate just before +22. Therefore, the maximum value of r1(t) (or r2(t)) is detected and converted into a pulse signal train tp(t,).

The product of this pulse interval tp and the falling speed V becomes the particle size d. Therefore, this particle size d becomes d-ΔtpXv (3).

Furthermore, the transmitted signal m(t) at the output end 121 or 122 has a pulse width t because there is a difference in level between the ore layer and the coke layer as shown in FIG. , tc can be easily determined. Therefore, using this, the ore layer thickness Qo and the coke layer thickness (lc) can be determined from the following equations.

Qo=t+)Xv, 12c==tcXv −
−(4) Thus r 1 (tL r 2 (t,)
, m (t) to the rate of descent V.

Particle size d9 Layer thickness Q. , Qc can be calculated.

FIG. 9 shows the drop rate V9 particle size d according to the present invention.

Ore layer thickness Q. , which shows an example in which the coke layer thickness Q'c was measured. As is clear from this figure, accurate measurements can be made. Although measurements are performed constantly, V, d, and Qor QC are calculated every 10 minutes.

Furthermore, in the present invention, measurements can be performed using a combination of two probes. Figure 10 shows the case where two wooden probes are attached to the belly of the blast furnace, and each probe measures directly reflected waves and transmitted waves.

At this time, the signals obtained from each probe have waveforms similar to those shown in FIG. Note that the distance between both probes was 30 cm.

The rate of descent is calculated from the delay in the transmission signals of the two probes, and the layer thickness and grain size are calculated in the same manner as before. The probe used in this case is shown in FIG. In this figure, 1 is a probe, 21+22 is an opening provided at its tip, 31+32 is a waveguide, 8 is a directional coupler, 9 is a heterodyne detector, 101 is an IF amplifier, and 1O2 is a detector. Detect waves. J4 is an oscillator, and 25 is a crystal detector, which detects directly reflected waves. The oscillator 14 is operated to radiate radio waves from the opening 21 to the charged material. The directly reflected wave is branched by the directional coupler 8 and then detected by the crystal detector 25. Further, the transmitted wave is detected by a detector 102 via a heterodyne detector 9 and an IF amplifier. The calculation circuit for the descending speed, layer thickness, and particle size has the same configuration as in Figure 7, but the descending speed is 2.
It is calculated from two transmitted signals.

As explained above, according to the present invention, various amounts of materials contained in a blast furnace can be detected with high precision using radio waves, and therefore greatly contribute to improvement of blast furnace operation.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of the probe used in the present invention, Fig.
The figure is a front view, Figure 3 is an explanatory diagram of the radio wave transmitting and receiving circuit, Figure 4 is an explanatory diagram showing the inside of the blast furnace, Figure 5 is an explanatory diagram showing an example of the measurement signal, and Figure 6 is the output from the switch. FIG. 7 is an explanatory diagram showing signals, FIG. 7 is a block diagram of a calculation circuit, FIG. 8 is an explanatory diagram showing cross-correlation coefficients, and FIG. 9 is a descending speed of a charge according to the present invention. FIG. 10 is an explanatory diagram showing another example of the present invention, and FIG. 11 is an explanatory diagram of a probe used in this example. 1 nib lobe 21,2. , : opening 31 r
32: Waveguide 41, 4. , :Gas injection lower 5:Cooling medium supply port 6:Discharge lower: Radio wave transmission/reception circuit 81, 82:Directional coupler 9+
192: Heterodyne detector 10+, +02: TF amplifier 11, . 112: Switch 1.21, 122. : Output end 13: Switching signal generator 14: Oscillator 15: Coaxial switch 1-61, 162: Coaxial waveguide converter 17ty172 Near isolator 18: Furnace wall 19: Coke layer 20: Ore layer 21: Cohesive zone 22: tuyere
23: Taphole 24: Hearth bottom 25: Crystal detector A: Charging surface B: Shirt 1 to part C
: Hearth part D=Morning glory part E: Hearth part Patent applicant Nippon Steel Corporation Black 2゛Draw force 4W time opening t (min) Rabbit 8v Horseman r4 Force 9 lecture ff11o'ff1 Child 11v

Claims (4)

[Claims] (1) Install one radio wave opening in the blast furnace close to the descending direction of the blast furnace charge, and alternately transmit radio waves into the furnace from the two openings at a speed sufficiently faster than the descending speed of the charge, A blast furnace characterized by measuring the descending speed, layer thickness, particle size, etc. of blast furnace charge from radio waves directly reflected from an opening and radio waves transmitted from one opening and received at the other opening. How to measure the charge. (2) The method for measuring blast furnace charge according to claim (1), wherein radio waves are transmitted from one opening and received from the other opening. (3) The method for measuring blast furnace charge according to claim (1), characterized in that radio waves are transmitted and received alternately from two openings. (4) A blast furnace charge with two openings provided at the tip of the probe, a radio wave transmission/reception circuit including an oscillator, directional coupler, detector, etc. connected to the openings, and the probe attached to the blast furnace wall. measuring device.