JPS5824724B2 - Burden level distribution measurement method in vertical furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring charge level distribution in a vertical furnace using a laser beam, and a bell-less material charging method using a chute that is free to rotate and tilt when charging the material to the vertical furnace. It is useful when applied when using a device.

BACKGROUND ART In recent years, when charging raw materials into a vertical furnace, particularly a blast furnace, it has become possible to distribute and charge arbitrary raw materials at arbitrary positions.

This is due to the development of a so-called bellless material charging device that uses a chute that can freely rotate and tilt.

When using these raw material charging devices, in order to take full advantage of their excellent characteristics and achieve stable furnace operation, it is necessary to check the level distribution of the charge in the furnace, its fluctuations (falling rate distribution), and the charging equipment. It is essential to accurately measure the layer thickness distribution, etc. of the raw material, and to correlate these measured values with various other indicators that indicate the operating status of the furnace, in order to optimize the raw material charging.

Conventionally, mechanical contact measurement methods such as sounding ronds have been the mainstream for level measurement of charges, but some non-contact measurement methods such as methods using microwave radar or methods using radiation have been used. It depends on the current situation.

However, in all of these conventional measurement methods, not only the measurement accuracy is not necessarily satisfactory, but also the level measurement is limited to only a certain position (point or line) on the surface of the charge, and it is difficult to measure the level on the entire surface of the charge. It has the disadvantage that it is impossible to measure the shape and that measurement takes a considerable amount of time.

Various methods for measuring the charge level distribution have been studied in order to eliminate such drawbacks, but for reasons specific to this technical field, a fully satisfactory measuring method has not yet been realized.

The unique reason for this is that in addition to problems with the measurement method itself, there are various measurement impeding factors in the space above the charge inside the furnace during operation.

Firstly, there is a constantly fluctuating high-temperature, high-pressure gas flow;
the presence of charge dust blown up by the gas flow;
Thirdly, there is the presence of heat rays emitted by the gas and the charge, and fourthly, there is the presence of vibrations and noise caused by the movement of the gas flow and the charge.

On the other hand, in recent years, progress has been remarkable in the field of laser engineering, and even with respect to infrared wavelength lasers, the wavelengths of both transmitters and detectors are diversifying, and the performance of equipment is rapidly increasing.

Therefore, the present invention is a method for measuring burden level distribution in a vertical furnace, taking into account the drawbacks that the above-mentioned prior art has due to the existence of the unique reasons, and the above-mentioned reasons and problems unique to the technical field that are hindering its improvement. Taking into account the recent developments in laser engineering, we will measure the surface level distribution of the charge in the vertical furnace and measure the descending velocity distribution of the charge, layer thickness distribution, etc. by using the measurement method. The object of the present invention is to provide a method for measuring burden level distribution in a vertical furnace that can be easily carried out with high precision and in a short time.

The basic principle used in the charge level measurement method of the present invention is triangulation using a light beam.

The principle of this triangulation method itself is well known and does not require further explanation, and when a ray of light is emitted from a certain position in a known direction and hits an object and is reflected, the point at a known distance from the emitted position is Methods of measuring distance by triangulation using the angle of incidence are also known in other specific fields, for example as range finders.

However, there are many requirements within an operating furnace that impede such measurements, and measurements in the art using light beams have been unsuccessful.

Although the present invention is based on the basic principle of triangulation, it incorporates the unique concept of the present invention to overcome various measurement impeding factors under operating conditions and measure the charge level in a vertical furnace. can be detected with high precision in a short time and over the entire surface of the charge.

When applying the optical measurement method to an operating vertical furnace, the characteristics required of the measurement light source are as follows.

(1) Luminous flux (
light beam) is not easily disturbed.

(2) The spread of the luminous flux is small and the attenuation due to light diffusion is small.

(3) Highly accurate measurement is possible by obtaining a narrow beam of light.

(4) There is little scattering of light due to floating dust in the gas flow.

(5) Not easily affected by optical noise existing in the furnace.

(6) Scanning can be performed easily.

The present invention utilizes a laser beam having coherent characteristics as a light source that best meets these conditions.

In other words, the laser beam is a pure monochromatic light that produces a luminous flux with a sharp outline without spreading, and there is no need to consider attenuation due to light spreading, as well as fluctuations in gas pressure and temperature and optical noise. It is less susceptible to influences and is convenient for high-precision measurements.

Furthermore, any desired light beam can be obtained using simple optical means, and scanning can be easily performed using simple optical means such as a rotating polygon mirror or electronic means.

The present invention focuses on the excellent characteristics of such a laser beam, and also uses a laser beam in the infrared region as a countermeasure against the light scattering phenomenon caused by floating dust in the gas, which is the biggest measurement inhibiting factor in measuring the burden level distribution in a vertical furnace. It also uses light with as long a wavelength as is technically and economically permissible.

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is an explanatory diagram conceptually showing the method of this embodiment, in which a laser beam transmitter 1 is
The optical center Gc of the detector 2 and the optical center Rc of the detector 2 (second
) are on the same level and in symmetrical positions across the furnace center of the vertical furnace 4, and the central axes of the laser beam transmitter 1 and the detector 2 are in the same vertical plane containing the furnace center line. This shows the case where

Scanning light A that is horizontally and vertically scanned over the entire furnace interior by a laser beam transmitter 1 using a suitable known method such as a rotating polygon mirror is emitted into the furnace through a transparent measurement window 3 (
(See Figure 1C).

At this time, the optical path of the scanning light A at a certain moment connects the optical center Gc and the optical center Rc of the projection Ao projected onto a horizontal plane including the optical center Gc of the laser beam transmitter 1 and the optical center Rc of the detector 2. Straight line

Let the angle with respect to the angle be α (see Figure 1).

Further, the projection A1 of the scanning light A onto a vertical plane including the optical center Gc and the optical center Rc is a straight line X connecting the optical center Gc and the optical center Rc.

Let γ be the angle with respect to (see Figure 1C).

The scanning light A reaches a point P on the surface of the charge 5 while being partially scattered by dust floating in the furnace gas 6, and a part of the reflected light, the reflected light B, is reflected through the measurement window. 3' and enters the detector 2.

At this time, the angle formed by the projection Bo of the optical path of the reflected light B on the horizontal plane including the optical center Gc and the optical center Rc and the straight line X□ connecting the optical center Gc and the optical center Rc is defined as β.

The reflected light (scattered light) Ba is the light that is scattered by floating dust etc. on the way from the laser beam transmitter 1 to the point P on the surface of the charge 5 and which enters the detector 2. Similarly, Bb indicates the light that does not enter the detector 2 out of the scattered light.

Now, with the distance between the optical center Gc of the laser beam transmitter 1 and the optical center Rc of the detector 2 being D, the straight line X□ passing through the optical center Gc and the optical center Rc is set as the Y axis, and at the furnace center O If the horizontal line perpendicular to the Y-axis is taken as the Y-axis, and the vertical line oriented at the furnace center 0 is taken as the Z-axis, the coordinates of point P on the surface of the charge 5 (
X, y, z) can be determined by the principle of triangulation, but as mentioned above, there are many difficulties in simply applying this method to the inside of an operating furnace.

Among them, the biggest obstacle is scattering due to floating dust in the gas.

Here, the particle size distribution of the dust, the wavelength of the scanning light, and the detector 2
The relationship between the intensity of the incident light and the intensity of the incident light on the detection surface 2a will be explained using FIGS. 2 and 3.

FIG. 2 is a schematic diagram conceptually showing the relationship of incident light to the detector 2 and the detection surface 2a, and details of the optical system are omitted.

In this embodiment, the detector 2 is a fixed type that has a field of view over the entire area inside the reactor, and the detection surface 2a is divided into, for example, a thin grid shape or grid pattern, and each part has a certain intensity. The structure is capable of detecting the presence or absence of the above incident light.

When the scanning light A is emitted into the furnace, the trajectory of the scanning light A is projected onto the detection surface 2a by the reflected light Ba, which is incident on the detector 2 among the light scattered by the dust, as shown by the broken line in Fig. 3a. Ru.

The projection of this trajectory starts from the end of the detection surface 2a, that is, the point G1 on the field of view limit, and continues until the projection P1 of the reflected light B at the point P on the surface of the charge 5.

That is, the position of projection P1 is seen as the end of a series of incident lights rather than a point.

The present invention focuses on this point, and when detecting the position of point P on the surface of charge 5, the position of projection P1 (in Fig. 3a) is determined as the end of the trajectory of scanning light A on detection surface 2a. (mth row, nth column) is selected and detected, and this is replaced with an angle and used for coordinate calculation.

Figure 3a shows scanning light A caused by reflected light Ba on the detection surface 2a.
This is shown by the broken line from 01 to Pl in the figure.

Figure 3 shows the relationship between the intensity distribution of incident light between 01 and P on the detection surface 2a and the particle size distribution of dust in the gas.When the wavelength is constant, it depends on the content of dust. When the average particle size is smaller than the wavelength of the scanning light A, the intensity distribution of the incident light is as shown by line 10 in the figure, and as the particle size becomes larger, it changes as shown by lines 11 and 12.

This is due to the fact that scattering increases rapidly as the particle size approaches the wavelength.

Also, regarding the distribution of line 10 or line 11 in Figure 3, the reason why the incident light intensity increases rapidly near the surface of the charge 5 is because the gas flow velocity locally increases near the surface of the charge 5. This is due to the fact that there are some areas where the particles are floating, and therefore the dust with large particles is flowing, making light scattering more likely.

As can be understood from Figure 3, when the wavelength is not very large compared to the dust particle size, the scanning light A is rapidly scattered before the light reaches the projection P, as shown by the curve of line 12 in the figure. Attenuation may occur, making it impossible to measure the projection P1 as the end position of the incident light on the detector 2.

As described above, since the main purpose of level detection according to the present invention is to detect the end of the incident light (the lower end of the incident light), it is necessary to obtain an incident light intensity distribution that is at least closer to line 10 than line 11 in Figure 3. For this purpose, it is necessary to select a light source that is in the infrared range and has as long a wavelength as technically and economically permissible.

Incidentally, even infrared laser light with a wavelength of several tens of microns, which has reached the practical level at present, is fully applicable to the purpose of the present invention, but considering the particle size distribution of dust in the gas, the final It is desirable to use a wavelength of about 500 μm or more.

In addition, as the detector 2, a detector with a detection sensitivity peak near the wavelength of the scanning light A is used, and a filter is used to remove noise components, etc., and by making use of the monochromatic characteristics of the laser light, the signal can be detected. An improvement in the noise ratio (SN ratio) can be obtained.

The detector 2 in this embodiment is of a fixed type, but is not limited thereto.

The detector 2 may be mounted so as to be movable up and down, left and right, and the central axis of the detector 2 may always be directed toward the lower end of the incident light using a servo mechanism attached to the detector 2.
By using the direction of the center' axis, the coordinates of the point P on the surface of the charge 5 can be calculated by the triangulation method as in the previous embodiment.

That is, the configuration is such that Pl is always at the position 01 in FIG. 3a.

FIG. 4 schematically shows a level distribution detection system used in the method of the present invention.

As shown in FIG. 4, a detection start signal S is sent from the electronic computer γ.
When 1 is output, the laser beam transmitter 1 and the detector 2 become ready for detection, and the protective shutters (not shown) of the measurement windows 3 and 3' are opened to start detection.

As detection progresses, momentary scanning angle signals S2 (corresponding to angles α and γ, for example) and one detection position signal S corresponding thereto
3 (corresponding to the angle β, for example) is input into the electronic computer 1, and the surface level of the charge 5 is subjected to coordinate calculation and stored (for example, the above-mentioned equations (1) to (3) are calculated).

When the termination command S4 is given and the detection is completed, the operation of the laser beam transmitter 1 and the detector 2 is stopped, and the protective shutters of the measurement windows 3, 3' are closed while entering a standby state for the next detection.

Based on the stored coordinates, the charge level distribution in the furnace is converted into a pattern (contour lines) and output to the display unit 8.

It is also possible to output the cross-sectional shape at any position and direction from the computer γ based on these contour lines.

As a matter of course, the charging sequence setting unit 1 also instructs the start or stop of charging based on the upper and lower limit levels of the charge 5 set in advance by the level detection sequence setting unit 9.
Served on 3rd.

Further, the charging control section 14 can also be controlled.

Furthermore, by comparing the obtained charge level distribution with the previous measurement value, the descending rate distribution of the charge over the time from the previous measurement to the current measurement can be determined.

However, no charging operation will be performed during this time.

On the other hand, the layer thickness distribution of the charge can also be obtained by comparing the measured values immediately before and after the charging operation.

At this time, the descending speed distribution and layer thickness distribution can also be output as a pattern display or a distribution display in an arbitrary cross section.

Any of the surface level distribution, descending speed distribution, and layer thickness distribution of the charge obtained in this manner shows a significant deviation compared to the preset optimal pattern, or locally abnormalities exceeding the allowable range. If there is a section that shows a value, other indicators that indicate the operating status of the furnace, such as temperature distribution, etc.
By comparing the gas component distribution, gas pressure distribution, gas flow velocity distribution, etc., it becomes possible to automate and optimize operations, such as issuing abnormality alarms and issuing correction commands regarding charging.

As described above, since the present invention performs measurement using a coherent laser beam, the measurement accuracy of surface level distribution measurement in a vertical furnace is good and the measurement time can be shortened.

Since the measurement accuracy is thus high, the layer thickness distribution of the charge can be easily obtained by comparing the surface level distribution data immediately before and after the charging operation.

Furthermore, since the measurement time is short, it is easy to obtain the descending velocity distribution of the charge.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram conceptually showing an embodiment of the present invention, in which a is a schematic side sectional view of a part of a vertical furnace, and b is an explanatory diagram schematically showing the X-Y plane coordinate relationship of the embodiment. In the figure, C is X-Y- of the same example.
An explanatory diagram schematically showing the Z three-dimensional coordinate relationship, Figure 2 is a schematic side view showing the relationship of incident light to the detection surface of the laser photodetector shown in Figure 1, and Figure 3a shows scattered light on the detection surface. Ba
Figure 4 is a graph showing the relationship between the intensity distribution of the incident light on the detection surface and the particle size distribution of dust in the gas, and Figure 4 is a graph showing an example of the trajectory of the scanning light A projected on the detection surface. FIG. 1 is a block diagram schematically showing a level distribution detection system. 1...Laser light transmitter, 2...Laser light detector, 3.3'...Measurement window, 4...
... Vertical furnace, 5 ... Charge, 6 ... Gas flow, 7 ... Electronic computer, 8 ... Display section, 9 ... ...Level detection sequence setting section, 13
...Charging sequence setting section, 14...
Charging control unit, Gc...optical center of transmitter 1,
Rc...Optical center of detector 2.

Claims (1)

[Claims] 1 The surface of the charge in the vertical furnace is scanned at various angles with a laser beam in the infrared region, and the laser beam is scattered by the dust present in the vertical furnace and the surface of the charge at each scanning angle. The surface level of the charge is measured by receiving the light and the reflected light on the detection surface of the light receiving means and detecting the end position of the locus drawn by the light receiving point, and the level distribution is determined according to the scanning. Method for measuring burden level distribution in a vertical furnace.