JPH0826386B2 - Slag level measuring device in furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is for measuring the slag level in a furnace using a microwave radar device for measuring the slag level in the furnace in a converter, a smelting reduction furnace and the like. It relates to the device.

[Prior Art] For example, during refining of a converter, slag floating on the surface of molten steel in the converter forms due to various conditions such as the composition and viscosity of the slag and the amount of oxygen in the slag. If such slag forming proceeds excessively, so-called sloping occurs, which adversely affects the molten steel composition, the total output steel yield, and the like. Furthermore, when slopping occurs, problems such as a decrease in work efficiency, a decrease in calorie of exhaust gas, a deterioration of work environment such as generation of red smoke, and a damage to the device occur.

On the other hand, from the viewpoint of preventing the slag from slopping, it may be considered to add a slag foaming inhibitor or to narrow down the amount of lance acid supply as a measure for reducing the amount of exhaust gas generated. Excessive addition of slag foaming agent raises the cost and deteriorates the thermal efficiency due to the decrease of the temperature inside the furnace, while the reduction of the amount of acid transfer causes a problem of prolonging the operation time due to the decrease of the reaction efficiency, that is, the deterioration of productivity. .

Therefore, in order to prevent the occurrence of sloping, it is necessary to quantitatively and accurately grasp the level of slag in the converter and to carry out proper converter operation, rather than simply predicting sloping.

For this reason, a technique for quantitatively measuring the slag level in the converter has been considered, and as its conventional technique, dust,
A radar-type level meter that uses microwaves that propagate in a straight line even under measurement environmental conditions in a converter where flames are present has been mainly tried.

As an example of a conventional slag level meter using a microwave radar system, there is the invention disclosed in Japanese Patent Laid-Open No. 63-21584. According to the present invention, an antenna of a microwave FMCW (Frequency Modulation Continuous Wave) type radar with a carrier frequency of about 10 GHz is fixed above the converter furnace body, and microwaves are transmitted toward the surface of the slag. The frequency deviation in the round-trip propagation time until it is reflected by the surface of the antenna and received again by the antenna is measured, and this is converted into a distance to measure the slag level.

However, since radio waves such as lances and furnace openings are present in the furnace in a narrow space, unnecessary reflected waves including multipath reflected waves are generated when transmitting micro-waves in the furnace. It is difficult to remove and accurately measure only the reflection signal from the surface of the slag.

Then, as a result of research to solve the above problems, the inventors of the present invention completed the invention of a distance measuring method and its device as Japanese Patent Application No. 63-250784, and filed a patent application.

The embodiments of the present invention disclose a technique relating to a microwave M-series radar type distance measuring method and an apparatus thereof using an M-series signal, which is a kind of pseudo-random signal, and the patterns are the same and the frequency is slightly different. Two different M-sequence signals are used, a microwave signal or a millimeter-wave signal of several tens GHz is used as a carrier, and a signal obtained by phase-modulating the carrier with the first M-sequence signal is used as a transmission signal from an antenna installed in the furnace. Transmitted to the slag surface in the furnace, for the reflected signal from the slag surface received by the receiving antenna,
Multiply the second M-sequence signal whose frequency is slightly different from that of the M-sequence signal used for modulation and perform coherent detection of the carrier wave to detect the weak reflected signal from the slag surface with high sensitivity, and use this signal with a low-pass filter. A pulse signal is obtained as a detection signal by integrating. Furthermore, a pulse signal is obtained as a time reference by multiplying the first and second M-sequence signals and integrating by a low pass filter,
From the time interval between the pulse of this time reference signal and the detection signal, measure the time delay of the signal between the transmitter and the receiver for signal propagation between the antenna and the slag surface, calculate the distance from the antenna to the slag surface, and The position of the slag surface is measured.

The present invention is not limited to M-sequence signals only, and the same operation can be performed using other pseudo-random signals.

[Problems to be Solved by the Invention] In the microwave radar type in-reactor slag level meter using the pseudo-random signal processing, the antenna and the in-reactor are determined from the time interval between the peaks of the detection signal and the pulse of the time reference signal. The distance from the slag level surface is calculated and good results have been obtained, but there are the following problems.

That is, in a smelting reduction furnace or the like, the fluctuation of the slag in the furnace is large, so that the change in the distance between the antenna and the slag surface, the change in the shape of the slag surface, the scattering of the slag, and the like cause the micro waves reflected by the slag surface to be received. The signal strength of the wave signal changes greatly. Therefore, when the reflected signal strength increases, signal saturation occurs in the amplifier in the radar device, and the detection signal waveform obtained as a result of signal processing is distorted and the peak of the detection signal pulse cannot be accurately detected. Measurement error occurs. On the other hand, when the reflected signal intensity decreases, the detection signal output also decreases, the S / N ratio deteriorates, and an erroneous signal peak may be measured due to the influence of noise, resulting in a measurement error.

The present invention solves the above-mentioned problems, and even when the fluctuation of the in-reactor slag level is severe, it is possible to measure the in-reactor level position normally. The purpose is to obtain a level measuring device.

[Means for Solving the Problem] A slag level measuring apparatus in a furnace according to the present invention includes (1) a first pseudo-random signal generating means and an output signal of the first pseudo-random signal generating means, which has the same pattern. A second pseudo random signal generating means having a slightly different frequency, and a first multiplier for multiplying the output of the first pseudo random signal generating means and the output of the second pseudo random signal generating means, Carrier wave generating means, and transmitting means for transmitting a signal obtained by modulating the output signal of the carrier wave generating means by the output of the first pseudo random signal generating means to a slug surface from a transmitting antenna inserted in the furnace as a transmission signal, Receiving means for receiving a reflected signal from the slag surface by a receiving antenna inserted in the furnace to obtain a received signal, an output of the receiving means and the second pseudo random signal generating means. Of the detected signal output from the detector, and a second multiplier that performs multiplication with the output of the second detector, a detector that detects the carrier wave output from the second multiplier, and outputs a reception strength signal. A microwave radar device comprising means for measuring a time difference between a time-series pattern and a time-series pattern of a multiplication value output from the first multiplier and outputting a level measurement value,
A signal strength which is inserted between the transmitting means and the transmitting antenna or between the receiving antenna and the receiving means, and which changes the microwave intensity signal input according to the received intensity signal output from the detecting means and outputs the signal. A variable device is provided.

(2) Further, in the invention of (1), an averaging calculator for averaging the level measurement values is provided instead of the signal strength varying device.

(3) Further, in the invention of the above (1), an averaging unit for averaging the level measurement values is provided.

(4) Furthermore, when the value of the reception intensity signal is lower than the set value, the averaging unit in the invention of (2) or (3) ignores the level measurement value at that time and performs the averaging process. It has a function to perform.

[Operation] The slag level measuring device in the furnace according to the present invention operates as follows. The first pseudo random signal and the second pseudo random signal having the same pattern and a slightly different frequency from the first pseudo random signal are respectively generated by the first pseudo random signal generating means and the second pseudo random signal generating means. A received signal obtained by transmitting a spread spectrum signal generated by phase-modulating a carrier wave from the first pseudo-random signal toward a slug surface by a transmitting means and receiving a reflected wave from the slug surface by a receiving means. , And the second pseudo-random signal is multiplied by the second multiplier. The multiplication result obtained as the output of the second multiplier is obtained when the modulated phase of the reception signal phase-modulated by the first pseudo random signal and the phase of the second pseudo random signal match. Is a carrier wave with the same phase,
Coherent detection is performed by the coherent detection means in the subsequent stage. The detected wave output is further output as a pulse-like slag level detection signal via a detection signal generating means composed of a pair of low-pass filters, a squarer and an adder.

However, the first and second pseudo-random signals have the same pattern of codes, but the frequencies of the signal generating means are slightly different, so the phases of both signals match (that is, the correlation output of both signals). From the maximum), the phase shifts as time passes, and if one code or more shifts, the correlation of the two pseudo random signals disappears. In this state, the phase of the carrier obtained as a result of multiplication of the received signal and the second pseudo-random signal is random, so the frequency band is limited by the low-pass filter that passes after the synchronous detection by the coherent detection means in the subsequent stage, No slag level detection signal is obtained.

When the time further passes and the phase between the first and second pseudo-random signals deviates by exactly one period of one pseudo-random signal, the phases again coincide with each other, and the correlation output of both signals becomes maximum. Therefore, the pulse-like slag level detection signal is obtained again through the coherent detection means and the detection signal generation means. Therefore, this phenomenon is repeated at regular intervals, and a periodic pulse signal is obtained as the slag level detection signal.

On the other hand, it is necessary to set a reference time in order to measure the time when the slag surface detection signal is obtained from the received signal, and this time reference signal is generated as follows. The time reference signal is a first pseudo random signal and a second pseudo random signal.
By directly multiplying by the multiplier of 1 and taking out the time series pattern as a result of the multiplication through a low-pass filter, a pulse signal having the same period as the slag level detection signal can be obtained.

Therefore, the time from the generation time of the time reference signal to the generation time of the slag level detection signal obtained from the reception signal is proportional to the propagation time of the electromagnetic wave back and forth between the transmission / reception antenna and the slug surface. The distance between the transmitting and receiving antenna and the slug surface is converted from the time between two signals.

 The operation of the present invention is formulated as follows.

The repetition frequency of the first pseudo-random signal is f ₁ , the second
The repetition frequency of the pseudo random signal is set to f _2, and the pattern of each pseudo random signal is the same. Where f ₁ ＞
f ₂

Letting T _B be the period at which the reference signal obtained by correlating the transmitted first pseudo-random signal and the second pseudo-random signal has a maximum value, the first pseudo-random signal included in this T _B is included. The difference between the wave numbers of the random signal and the second pseudo-random signal is the wave number N of exactly one cycle.

That is, T _B · f ₁ = T _B · f ₂ + N When the above formula is rearranged, T _B is given by the following formula [1].

T _B = N / (f ₁ −f ₂ ) ... [1] That is, the smaller the difference between the two clock frequencies, the larger the period T _{B at} which the reference signal becomes the maximum value.

Next, the carrier wave phase-modulated by the first pseudo-random signal is transmitted, reflected at the slag level, and the propagation time until it is received again is τ, and this received signal is demodulated by the second pseudo-random signal. , The time at which the pulsed signal of the slag level detection signal obtained by coherent detection is generated,
The time difference measured from the pulse signal generation time of the reference signal
When T _D, the wave number of the second pseudo random signal generated between T _D, from the wave number of the first pseudo random signal generated between T _D, the wave number of the first pseudo-random signal generated at τ time Since there are only a few, the following formula is established.

T _D · f ₂ = T _D · f ₁ −τ · f _{1 When the} above formula is rearranged, T _D is given by the following formula [2].

T _D = τ ・ f ₁ / (f ₁ -f ₂ ) ... [2] That is, the propagation time τ is temporally expanded or slowed by f ₁ / (f ₁ -f ₂ ) times. Measured as _D. By extending the measurement time, it can be said that the present invention is a slag level measuring device suitable for short distance measurement.

Here, the propagation time τ is τ = 2x / v, where v is the propagation velocity and x is the distance to the slag surface. Therefore, the following equation [3] is obtained from equation [2].

The distance x can be measured by measuring the time difference T _{D according} to the equation [3].

In the carrier coherent detection means in the present invention, a part of the output of the transmission carrier generation means is taken out from the first distributor, and this is output from the hybrid coupler to the in-phase component (in-p).
hase component) I and quadrature componen
t) Q and the carrier wave output from the second multiplier is divided into signals R ₁ and R ₂ by a _second divider, and the signal I and the signal R ₁ are divided into a third multiplier. The multiplication value I · R ₁ and the multiplication value Q · R ₂ obtained by multiplying the signal Q and the signal R ₂ by the fourth multiplier are respectively obtained as the detected signal.

Further, in the present invention, the time difference measuring means of the time series pattern of the multiplication value of the first multiplier and the time series pattern of the detected wave signal, the output of the first multiplier is bandpassed by the first low pass filter. The maximum value generation time of the pulse-shaped reference signal obtained by limiting and the multiplication values I · R ₁ and Q · R ₂ of the third and fourth multipliers are respectively band-passed by the second and third low-pass filters. The signal obtained by limiting is the first
And the second squarer respectively performs square calculation, and the time between the maximum value generation time of the pulsed detection signal obtained by calculating the sum of the squared values of the calculation results by the adder is measured. It is measured by a container.

Furthermore, when the reflected signal from the slag surface in the furnace becomes large, the signal strength variable device attenuates the transmitted signal or the received signal so that the signal does not saturate inside the microwave data device, and the reflected signal strength changes. When becomes smaller, the transmission signal or the reception signal is amplified, and the signal strength is adjusted so that the signal level inside the microwave radar device is always constant.

The average calculator inputs the level measurement value and the reception intensity signal from the microwave radar device, and averages the level measurement values obtained within an arbitrary time. In this average calculation, when the value of the reception intensity signal is smaller than the set value, the level measurement value at that time is ignored and the average calculation is performed, and the average position of the slag level in the furnace is obtained and displayed.

[Embodiment] FIG. 1 is a schematic view of a converter in which the present invention is implemented, FIG. 2 is a block diagram of an embodiment of a microwave radar device forming an essential part of the present invention, and FIG. FIG. 4 is a waveform diagram for explaining the operation, and FIG. 4 is a configuration diagram of a 7-bit M-sequence signal generator.
(45) is a shift register having a seven-stage structure, and (46) is an exclusive OR circuit.

In FIG. 1, (1) is a smelting reduction furnace, (2) is molten steel, (3) is slag, (4) is a hood, and (5) is a lance. (6) is a measuring device having a microwave radar device as a main part, and is connected to a transmitting antenna (7) and a receiving antenna (8) through a waveguide, and both antennas (7),
(8) is inserted into the furnace through the hole provided in the hood (4), and the level of the slag (3) in the furnace is measured.

Next, the operation of the present invention will be described with reference to FIGS. 2 and 3 and 4. In FIG. 2, (10) is a microwave radar device which constitutes a main part of the measuring device (6), and this is basically the same as the invention of Japanese Patent Application No. 63-250784.

In the microwave radar device (10), the pseudo-random signal generators (18) and (19) can be M-sequence signal generators, for example. FIG. 4 shows the configuration of a 7-bit M-sequence signal generator, which is composed of, for example, a 7-stage shift register including ECL (emitter coupled logic) elements and an exclusive OR circuit (46). . The M-sequence signal is a cyclic circulating signal which is a combination of codes "1" (corresponding to + E of a positive voltage) and "0" (corresponding to -E of a negative voltage). In this case, one cycle is completed when 2 ⁷ -1 = 127 signals (also referred to as 127 chips) are generated, and a circulation signal is generated by repeating this cycle. Since the pseudo random signal generators (18) and (19) are composed of the same circuit, the output signals of both are signals of exactly the same pattern.
However, since the supplied clock frequencies are slightly different, the one cycle is also slightly different. Further, as the pseudo random signal, in addition to the M series signal, the Gold series signal,
JPL sequence signals can be used.

The clock generators (16) and (17) both have a built-in crystal oscillator and generate a stable clock signal with a sufficient frequency, but the generated frequencies are slightly different. In this embodiment, the generation frequency f ₁ of the clock generator (16) is 100.004 MHz,
The frequency f ₂ generated by the clock generator (17) is 99.996 MHz, and the frequency difference is f ₁ -f ₂ = 8 kHz.

The clock signals f ₁ and f ₂ output from the clock generators (16) and (17), respectively, are supplied to the pseudo random signal generators (18) and (19), respectively. The pseudo-random signal generators (18) and (19) output the M-sequence signals M ₁ and M ₂ of the same pattern, although each cycle is slightly different due to the frequency difference of the driving clock signals. Now, when the periods of the two M-sequence signals M ₁ and M ₂ are obtained, the period of M ₁ = 127 × 1 / 100.004 MHz≈1269.9492 ns, and the period of M ₂ = 127 × 1 / 99.996 MHz ≈1270.0508 ns. That is, the two M-sequence signals M ₁ and M ₂ are approximately 1270 ns (10
^-9 seconds), but there is a time difference of about 0.1 ns between the two periods. Therefore, if these two M-sequence signals M ₁ and M ₂ are generated by being circulated and the patterns of the two M-sequence signals match at a certain time ta, _a deviation of 0.1 ns is generated every time period elapses. Occurs between both signals, and after 100 cycles, a deviation of 10 ns occurs between both signals. Here, the M-sequence signal is 12
Since seven signals are generated, the generation time of one signal is 10 ns. Therefore, the occurrence of a shift of 10 ns between the two M-sequence signals M ₁ and M ₂ corresponds to a shift of one M-sequence signal. The output M ₁ of the pseudo random signal generator (18) is supplied to the multipliers (20) and (13), and the output M ₂ of the pseudo random signal generator (19) is supplied to the multipliers (20) and (23). To be done.

The carrier wave generator (11) oscillates, for example, a microwave having a frequency of about 10 GHz, and its output signal is distributed by the distributor (12) and supplied to the multiplier (13) and the hybrid coupler (15). The multiplier (13) is composed of, for example, a double balanced mixer, and multiplies a carrier having a frequency of about 10 GHz input from the distributor (12) and the M-sequence signal M ₁ input from the pseudo-random signal generator (18). To output a spread spectrum signal with the carrier phase modulated, and the transmitter (14)
Supply to The transmitter (14) power-amplifies the input spread spectrum signal, converts it into an electromagnetic wave through the transmitting antenna (5), and radiates it into the furnace (1). Frequency here
The wavelength of 10 GHz electromagnetic waves in the air is 3 cm, which is sufficiently longer than the particles of dust or smoke in the furnace (1), so it is not easily affected by dust.

The transmitting antenna (7) and the receiving antenna (8) are, for example, horn antennas, and the directivity is sharply narrowed to minimize the reflected power from other than the slag surface. The antenna gain is about 20 dB. The electromagnetic wave radiated from the transmitting antenna (7) toward the inside of the furnace (1) is reflected on the surface of the slag, converted into an electric signal via the receiving antenna (8), and input to the receiver (22). The timing at which the input signal is supplied to the receiver (22) is, of course, from the timing at which the electromagnetic wave is radiated from the transmitting antenna (7), the electromagnetic wave reciprocates the distance to the slag surface in the furnace (1), and the receiving antenna ( It is delayed by the propagation time of the electromagnetic wave until it reaches 8). The receiver (22) amplifies the input signal and supplies it to the multiplier (23).

On the other hand, the multiplier (20) is multiplied by the M-sequence signals M ₁ and M ₂ input from the pseudo-random signal generators (18) and (19), respectively, and the time-series signal of the multiplication value is sent to the low-pass filter (21). Supplied. FIG. 3A is a waveform showing an input signal to the low-pass filter (21), that is, a time-series signal as a multiplication value of the multiplier (20), which is input to the multiplier (20). When the phases of the two pseudo-random signals match, the + E output voltage continues, but when the phases of the two signals do not match, + E and -E output voltages are randomly generated.

When the low-pass filters (21), (27), (28) have a kind of integration function by limiting the frequency band, and the phases of both signals match as the integrated signal of the correlation calculation value of both signals. Outputs a pulsed signal as shown in FIG. When the phases of the two signals do not match, the output becomes zero. Therefore low-pass filter (21)
A pulsed signal is periodically generated at the output of. This pulsed signal is supplied to the time measuring device (32) as a time reference signal. In the case of the present embodiment, the period T _B of this reference signal is a pseudo-random signal that is a 7-bit M-sequence signal M ₁ and M _2.
Therefore, the wave number N of one cycle is 2 ⁷ −1 = 127, and f ₁
= 100.004MHz, f ₂ = 99.996MHz, so T _B = 15.875m
s. This reference signal and its period TB are shown in Fig. 3 ( _D ).
Shown in.

Further, the multiplier (23) receives the received signal from the receiver (22) and the M-sequence signal M ₂ from the pseudo random signal generator (19).
Is input, and both signals are multiplied. The multiplication result of the multiplier (23) is the modulated phase of the reception signal in which the transmission carrier wave is phase-modulated by the first M-sequence signal M ₁ and the second
When the phases of the M-sequence signal M ₂ of M are matched, they are output as carrier signals having the same phase, and the modulated phase of the received signal and M
When the series signals M ₂ have different phases, they are output as carrier waves having random phases and supplied to the distributor (24).

The divider (24) divides the input signal into two and supplies the divided outputs R ₁ and R ₂ to the multipliers (25) and (26), respectively. The hybrid coupler (15), to which a part of the carrier wave for transmission is supplied from the distribution supply (12), has a signal I of in-phase component (phase 0 degree) and a quadrature component (phase 90 degree) with respect to the input signal. ) Signal Q and outputs it as multipliers (25) and (2
6) Supply to. The multiplier (25) is a hybrid combiner (1
5) The signal I input from the carrier oscillator (11) (ie, the signal in phase with the output of the carrier oscillator (11)) is multiplied by the signal R ₁ input from the distributor (24), and the multiplier (26) inputs The signal Q (that is, a signal having a 90 ° phase difference from the output of the carrier wave oscillator (11)) and the signal R ₂ are multiplied to obtain a phase 0 ° component (I · R ₁ ) and a phase 90 ° in the received signal, respectively. Ingredient (Q
・ R ₂ ) and are extracted and output as the detected wave signal. The signals I · R ₁ and Q · R ₂ as the detected wave signals are supplied to the low-pass filters (27) and (28), respectively.

The low-pass filters (27) and (28) have an integration function by limiting the frequency band, and integrate the correlation calculation values of two signals. That is, the signal R input from the output of the multiplier (23) to the multiplier (25) via the distributor (24).
_{When 1} and the phase of the signal I input to the multiplier (25) from the hybrid coupler (15) match, the phase of the signal R ₂ and the signal Q similarly input to the multiplier (26) match. At this time, the output signals of the multipliers (25) and (26) are pulse signals of constant polarity (voltage + E pulse signal),
Low-pass filters (27) and (28) that integrate this signal
A large positive voltage is obtained at the output of. When the phases of the signal R ₂ and the signal I do not match, and when the signals R ₁ and Q are
When the phases of the signals do not match, the output signals of the multipliers (25) and (26) become positive and negative polarity pulse signals (that is, voltage + E and -E pulse signals) that randomly change, respectively, and these signals were integrated. The outputs of the low pass filters (27) and (28) become zero. The phase 0 degree component integrated by the low pass filters (27) and (28) as described above and the phase 90
The signal of the degree component is supplied to squarers (29) and (30), respectively. The squarers (29) and (30) respectively square the amplitude of the input signal and supply the output signal of the calculation result to the adder (31). The adder (31) adds both input signals and outputs a pulsed detection force signal as shown in (c) of FIG. 3 and supplies it to the time measuring device (32).

Now the maximum value occurrence time of the detection signal and t _b. In this way, the phase 0 degree component and the phase 90 degree component of the transmission carrier wave are respectively detected from the signal obtained by the correlation processing between the reception signal and the M-sequence signal M _2, and the detected signal is squared after the integration processing. The method of calculating and obtaining the slag level detection signal as the sum of the pair of squared values has a slightly complicated configuration, but a highly sensitive slag level detection signal can be obtained. Further, since the correlation output of the pseudo-random signal such as the M-sequence signal is obtained, the influence of noise is reduced and the signal is emphasized. Therefore, it is possible to realize a measurement system having a high signal-to-noise ratio (S / N). it can. Of course, as a carrier wave detection method, there is a detection method using a crystal, which reduces the sensitivity,
Since the configuration is simplified, this method can be adopted depending on specifications and costs.

The time measuring device (32) is _a time when the maximum value of the reference signal input from the low pass filter (21) is t _a, and an adder (31)
The time T _D between the occurrence time t _b of the maximum value of the detection signal input from and is measured. Therefore, the time measuring device (32) has a function of detecting the maximum value generation time of the two input signals. For example, the input voltage value is sequentially sampled and held by the clock signal, and the sampled value by the current clock signal,
The maximum value generation time of the input signal is detected by sequentially comparing the sample value immediately before the clock signal with the voltage ratio meter and detecting the time when the input signal changes from the increasing state to the decreasing state with respect to time. can do. The time
T _D is the maximum value generation time of the reference signal shown in Fig. 3 (d)
and t _a, shown as the time between the maximum generation time t _b of the detection signal shown in (c).

(35) is a signal strength variable device, which is provided between the receiving end of the microwave radar device (10) and the receiving antenna (8) inserted in the furnace in this embodiment, the microwave radar device ( It may be provided between the transmitting end of 10) and the transmitting antenna (7). (42) is an averaging unit provided on the output side of the microwave radar device (10), and (43) is a CRT display unit.

FIG. 5 shows an embodiment of the signal strength varying device (35). A control signal is obtained from the peak value of the reception intensity signal input from the microwave radar device (10) and is input to the variable attenuator (41). The variable attenuator (41) attenuates the signal in proportion to the signal strength of the input control signal, and when the control signal is not input, the signal is passed as it is.

In the signal strength varying device (35) of the present embodiment, the reception strength signal from the adder (31) of the microwave radar device (10) is input to the dead zone circuit (36) so that the input signal has a constant level. If it does not reach, the control signal is not output and the signal is not attenuated in the variable attenuator (41). When a signal exceeding the limit value of the dead zone circuit (36) is input, this signal is amplified by the amplifier (37) and then the peak hold circuit (3
Entered in 8). And this peak hold circuit (3
8) has a time constant similar to the cycle of the input pulse signal and holds and outputs the peak value of the input pulse. The control signal for the variable attenuator (41) is obtained by adding an amplification and an offset to the held signal by the amplifier (39), and the amount of attenuation in the variable attenuator (41) is determined.

FIG. 6 shows a state in which signals are actually controlled by the signal strength varying device (35).

FIG. 6 (a) shows the operation of the signal strength varying device (35),
It shows a change in the output of the control signal with respect to the received reception intensity signal, that is, a change in the attenuation amount of the variable attenuator (41). The control signal becomes a signal proportional to the reception intensity signal when the reception intensity signal is equal to or more than the limit value determined by the dead zone circuit (36). In this embodiment, the limit value is 0.7V, and the control signal is output when the maximum value of the reception intensity signal is 0.7V or more.

FIG. 6 (b) is a diagram showing the state of the signal level of the entire measuring device (6), showing the relationship between the reflected signal intensity received by the receiving antenna (8) and the received intensity signal. In the region where is small, the value of the received strength signal is also small and the signal strength is not attenuated by the signal strength variable device (35).
Although the reflected signal strength is proportional to the received strength signal, even if the reflected signal strength changes by several tens of dB as the reflected signal strength increases, the signal strength is changed by the signal strength variable device (35). , It became possible to suppress the change of the reception intensity signal to be small.

The flow of the average calculation processing in the average calculator (42)
Shown in the figure. The average calculator (42) inputs the level measurement value from the distance integrator (33) of the microwave radar device (10) and the received intensity signal from the adder (31), and the peak value of the received intensity signal is arbitrary. When it is larger than the set value, the input level measurement value is added to the sum sum of the level values, and when the received intensity signal is smaller than the set value, the input level measurement value is not added. When the time of the next addition period reaches the set value, the sum sum of the level values is divided by the number of times the level measurement values are added to obtain the average slag level, and the sum sum of the level values is zero. As a preparation for the next average value calculation, the process returns to the beginning of the process to input the next signal.
If the time of the addition period has not reached the set value, the process directly returns to the next signal input.

In addition, in the present embodiment, these average calculation processes were performed using a personal computer, and the calculation result of the average slag level was output to the display unit (43) (CRT).

As described above, according to the present invention, the carrier wave phase-modulated by the first pseudo-random signal is transmitted toward the slag surface, and the received signal obtained by reflecting from the slag surface and the second signal are obtained. Time series pattern of the detected signal obtained by detecting the carrier wave obtained by multiplying by the pseudo random signal and the time series of the multiplication value obtained by directly multiplying the first and second pseudo random signals Since the distance to the slag surface where the time difference from the pattern is measured is measured, the following effects can be obtained.

(1) Since it is a non-contact measurement, the durability of the sensor part such as the antenna can be secured, and the installation of the device is easy and the maintenance is easy.

(2) Since continuous measurement is possible, measurement with high responsiveness is possible.

(3) Since the measurement using the conventional high-speed signal is converted into the low-speed signal by the circuit of the present invention, the inexpensive and small-sized device can be realized. Moreover, adjustment becomes easy.

(4) As a means for detecting a carrier wave reflected from the slag surface and subjected to correlation processing after reception, to obtain a detection signal, an in-phase component and a quadrature component of the transmission carrier wave are extracted from the carrier wave subjected to correlation processing, and low-pass filters are respectively applied. Since the squared calculation is performed and addition is performed to obtain the detection signal, the slag level can be detected with extremely high sensitivity.

(5) The received signal transmitted from the carrier wave phase-modulated by the first pseudo-random signal and reflected from the slug surface is
By the method of obtaining the carrier wave that has been correlated with the second pseudo-random signal having the same pattern and the same frequency as the first pseudo-random signal, the measurement time between the detection signal from the slug surface and the reference signal can be measured on the time axis. Since it is greatly expanded (12,500 times in this example), not only can the distance of the slag surface be accurately measured from a short distance, but also desired reflection signals from the slag surface and unnecessary reflection signals from outside the target range. Can be clearly distinguished and separated on the time axis of generation of the detection signal. Therefore, when measuring the slag level in the furnace, even in a measurement environment in which unnecessary reflected waves are likely to occur in a narrow space such as in the furnace, the unnecessary reflected waves can be removed and stable slag level measurement can be performed.

(6) Further, even when the intensity of the microwave reflection signal on the slag surface changes with the variation of the slag surface in the furnace, the fluctuation of the detection signal intensity is suppressed by adjusting the signal intensity by the receiver, It is possible to suppress the occurrence of errors due to saturation and a decrease in signal level, and more accurately measure the slag level position in the furnace.

(7) Even if the signal level temporarily decreases due to a sudden change in the slag level, the average value of the measured values is ignored by ignoring the measured values with a poor S / N ratio, and Accurate measurement has become possible.

[Brief description of drawings]

1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the embodiment of the present invention, FIG. 3 is a waveform diagram for explaining the operation of FIG. 2, and FIG. 4 is a 7-bit M series. 5 is a block diagram showing an embodiment of a signal strength varying device, FIG. 6 is a diagram showing its operation, and FIG. 7 is a flowchart showing a signal processing flow of an averaging unit. is there. (1) ... Melt reduction furnace, (2) ... Molten steel, (3) ... Slag, (5) ... Lance, (6) ... Measuring device, (7)
...... Transmission antenna, (8) …… Reception antenna, (10)…
… Microwave radar equipment, (11) …… Carrier wave oscillator,
(12), (24) …… Distributor, (13), (20), (23),
(25), (26) …… Multiplier, (14) …… Transmitter, (15)
...... Hybrid coupler, (16), (17) …… Clock signal generator, (18), (19) …… Pseudo random signal generator, (21), (27), (28) …… Low pass filter ,
(22) …… receiver, (29), (30) …… squarer, (3
1) Adder, (32) ...... Time measuring device, (33) ...... Distance converter, (35) ...... Signal strength variable device, (42) ...... Average calculator.

Claims (4)

[Claims] 1. A first pseudo-random signal generating means, a second pseudo-random signal generating means having the same pattern as that of the output signal of the first pseudo-random signal generating means and having a slightly different frequency, and the first pseudo-random signal generating means. A first multiplier for multiplying the output of the pseudo random signal generating means and the output of the second pseudo random signal generating means, a carrier generating means, and the carrier generating by the output of the first pseudo random signal generating means. Transmitting means for transmitting a signal obtained by modulating the output signal of the means to a slug surface from a transmitting antenna inserted in the furnace as a transmission signal, and a reflection signal from the slag surface being received by a receiving antenna inserted in the furnace. Receiving means for obtaining a received signal,
A second multiplier that multiplies the output of the receiving unit and the output of the second pseudo random signal generating unit, and a carrier wave output from the second multiplier is detected to output a reception intensity signal. Detection means, and means for measuring the time difference between the time series pattern of the detected signal output from the detection means and the time series pattern of the multiplication value output from the first multiplier to output a level measurement value. A microwave radar device, which is inserted between the transmitting means and the transmitting antenna or between the receiving antenna and the receiving means, and is input in accordance with a reception intensity signal output from the detecting means. An apparatus for measuring slag level in a furnace, comprising a signal strength varying device for changing and outputting an intensity signal. 2. The slag level measuring apparatus in a furnace according to claim 1, wherein an averaging calculator for averaging the level measurement values is provided in place of the signal strength varying device. 3. A slag level measuring apparatus in a furnace according to claim 1, further comprising an averaging unit for averaging the level measurement values. 4. The averaging unit has a function of ignoring the level measurement value at that time and performing an averaging process when the value of the reception intensity signal is lower than a set value. The slag level measuring device in the furnace according to the item (2) or (3).