JPH10307053A - Apparatus for detecting level of lump of substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus which can detect a level of a scattering substance such as a scrap or the like stably for a long time even when the scrap is thrown in and even in an ambience where dust easy to adhere is floating. SOLUTION: The apparatus detects a load height of a particle substance or a mass of substance loaded in a storing tank 1. One or more pairs of nozzles 2 are arranged at opposite positions on the same horizontal plane in the storing tank 1 in a plurality of stages in a vertical direction of the tank. A transmitter 9a of a microwave level detection sensor is set to one of the pair of the nozzles 2, and a receiver 9b is set to the counterpart of the pair. A purge system 17 is also provided to blow the air or an inert gas between a sensor 9 of each nozzle 2 and the storing tank 1. The purge system 17 uses both a high-speed purge whereby a flow velocity in the nozzle is high and a low-speed purge whereby the flow velocity in the nozzle is low. The high-speed purge is carried out intermittently, while the low-speed purge is executed continuously. If two or more pairs of the microwave level detection sensors 9 are set on the same horizontal plane, different microwave frequencies are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a level of a bulk material, which measures the level of a granular or bulk material such as scrap accumulated in a tank.

[0002]

2. Description of the Related Art Scrap iron is put into an arc furnace for steel making to produce steel. This scrap is put into a scrap preheating tank, and after being preheated, put into an arc furnace. For this reason, the scrap level in the scrap preheating tank must be accurately measured, and an appropriate amount of scrap must always be supplied to the arc furnace.

Next, a conventional apparatus for measuring the level of scrap will be described. FIG. 5 shows the situation of the level measurement sensor 9 and the scrap 21 attached to the scrap preheating tank 1. Sensors 9 are set on the body of the scrap preheating tank 1 at a constant pitch in the height direction. The upper part of the body is a hopper 22, and this hopper 22
A scrap 9 is loaded from above, and the scrap level of the body is measured by the sensor 9. The sensor 9 is attached to the nozzle 2, and the nozzle 2 is attached in a pair at opposite positions at the same height on the body. Sensor 9
Is composed of a microwave transmitter 9a for transmitting microwaves and a microwave receiver 9b for receiving the transmitted microwaves. A microwave transmitter 9a is provided on one of the pair of nozzles 2 and a microwave receiver is provided on the other. A vessel 9b is provided.

[0004] The level measurement of the scrap 21 is based on the fact that the sensor 9 located vertically above and below cannot receive the microwave transmitted by the presence of the scrap 21,
When the upper sensor 9 can receive the microwave, it is measured that there is a scrap 21 level between the two sensors 9.

FIG. 6 is a sectional view taken along the line X in FIG. The nozzle 2 communicates with the scrap preheating tank 1, and a sensor mounting flange 50 is provided at the nozzle tip, and the sensor 9 is mounted via the sensor mounting flange 50.

FIG. 7 also shows the X section of FIG. 5, but a seal plate 51 is provided between the nozzle 2 and the scrap preheating tank 1 to prevent dust 20 and scrap 21 from entering the nozzle 2. . The seal plate 51 is made of a material that transmits microwaves, for example, Teflon.

FIG. 8 shows another level measuring device. A hopper 22 is provided above the scrap preheating tank 1, and a sounding device 60 is provided inside the scrap preheating tank 1 around the hopper 22. A weight 62 is connected to the sounding device 60 via a wire 61. Unwind the wire 61 until 62 hits the top of the scrap 21,
The level of the scrap 21 is measured by measuring the unwinding amount of the wire 61 by the sounding device 60. When the scrap 21 is inserted, the weight is wound up so that the scrap 21 does not hit as shown in the standby state.

FIG. 9 shows still another level measuring device.
A chamber 63 is provided near the lower part of the hopper 22 of the scrap preheating tank 1, and a bogie 64 on which a sounding device 60 is mounted runs in the chamber 63. A weight 62 is connected to the sounding device 60 via a wire 61.
The level of the scrap 21 is measured from the unwinding amount of the wire 61 when the wire 2 is lowered to reach the top of the scrap 21. The position indicated by the broken line indicates the standby position of the truck 64 when the scrap is put.

[0009]

In the case of the nozzle 2 shown in FIG. 6, since the scrap 21 and the dust 20 enter because the nozzle 2 is in communication with the scrap preheating tank 1, measurement becomes impossible.
The inside of the nozzle 2 must be cleaned frequently. In the case of the nozzle 2 shown in FIG. 7 in which this is improved, the scrap 21 and the dust 20 do not enter the nozzle 2, but if the dust 20 adheres to the surface of the seal plate 51 on the scrap preheating tank 1 side and becomes thick, measurement becomes impossible. . For example, when measuring with a microwave, measurement becomes impossible when the thickness of the attached dust 20 is about 5 mm. Oil may be attached to the scrap 21, and since the preheating gas 23 also has moisture, oil, and the like, the dust 20 has a small amount of tackiness and adheres to the seal plate 51. Since the dust 20 is fine powder of the scrap 21,
And the microwave is cut off, so that the measurement is made as if there is no scrap 21, and the correct measurement cannot be performed.

After the scrap 21 is preheated, the scrap 21 is supplied into an arc furnace (not shown) and decreases, so that the next scrap 21 is put into the scrap preheating tank 1 again. At this time, in the apparatus shown in FIGS.
Measurement becomes impossible. In the case of the apparatus shown in FIG. 8, the size d of the hopper 22 is smaller than the diameter D of the scrap preheating tank 1 because the sounding device 60 is disposed, and the scrap 21 is easily clogged in the hopper 22. If the hopper 22 is made larger, the equipment becomes larger.

The present invention has been made to solve such a problem. That is, it is possible to provide a level detection device for a lump-like substance that can detect even at the time of throwing in a scrap and can stably detect the level of a bulky substance such as scrap over a long period of time even in an atmosphere in which dust that easily adheres is flying. With the goal.

[0012]

To achieve the above object, according to the first aspect of the present invention, there is provided a level detecting device for detecting a loading height of granular or massive substances loaded in a storage tank. At least one pair at the opposite position on the horizontal plane,
In addition, nozzles are arranged in pairs in multiple stages in the tank vertical direction,
One pair of nozzles is provided with a transmitter of a microwave level detection sensor, and the other is provided with a receiver, comprising a purge system for blowing air or an inert gas between the sensor of each nozzle and a storage tank, The purge system uses a high-speed purge in which the flow rate in the nozzle is high and a low-speed purge in which the flow rate in the nozzle is low.
When low-speed purging is performed continuously and two or more pairs of microwave level detection sensors are arranged on the same horizontal plane, different microwave frequencies are used.

[0013] A microwave transmitter is provided on one of the nozzles provided opposite to each other at the same height, and a microwave receiver is provided on the other, and when microwaves can be received,
It is known that the scrap has not reached the level of the pair of nozzles, and if reception is not possible, it is known that the scrap has reached the level of the pair of nozzles. A purge system that blows gas into the tank is connected to each nozzle, and dust and scrap that have already entered the nozzle are blown into the tank by high-speed purging to prevent dust and scrap from entering. The low-speed purge also prevents dust from entering. When two or more pairs of microwave level detection sensors are provided on the same horizontal plane,
By using different microwave frequencies from each other, erroneous detection can be prevented.

According to the second aspect of the present invention, two flanges are provided at the outer end of the tank of each of the pair of nozzles, and a seal plate for blocking passage of the substance in the tank is detachably attached between the flanges. The transmitter or the receiver is provided outside the flange via an anti-vibration damper.

Since the passage of dust and scrap is prevented by the seal plate, the dust and scrap are prevented from hitting the microwave level detection sensor, so that the detection accuracy can be prevented from being deteriorated or damaged. In addition, by attaching the microwave level detection sensor to the nozzle via the vibration damper, it is possible to protect the nozzle from impact at the time of scrap input.

According to the third aspect of the present invention, the high-speed purge in the purge system is 10 m / sec or more, and the low-speed purge is 1 m / sec.
It is set at less than 0 m / sec, desirably at least 1 to 2 m / sec, low-speed purge is performed continuously with all nozzles, and high-speed purge is performed periodically for each nozzle or for one or more pairs of groups. Purge for a period of time.

It has been experimentally found that dust and scrap entering the nozzle should be purged at 10 m / sec or more in order to blow the dust and scrap into the tank. This high-speed purge is performed for each nozzle or for one or more pairs of groups.
It has also been experimentally found that periodically purging for a certain period of time is effective. It has also been experimentally confirmed that low-speed purging at 1-2 m / sec is most effective in preventing dust from entering.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal section showing the configuration of the scrap preheating tank 1. FIG. 2 shows X-
2 shows an X cross section, showing the arrangement of the nozzle 2 and the sensor 9 at the same level. FIG. 3 shows a detailed view of the nozzle 2. FIG. 4 shows an air purge sequence according to the present embodiment.

In FIG. 1, a hopper 22 is provided on an upper portion of a cylindrical body of a scrap preheating tank 1, and nozzles 2 are horizontally provided at a constant pitch in a height direction on the body. Scraps 21 are supplied from the hopper 22 and are deposited on the body. A preheating gas is supplied from the lower part of the body to preheat the scrap 21. The nozzles 2 provided at the same level form a pair and are arranged to face each other. A sensor 9 is attached to the tip of the nozzle 2, the sensor 9 includes a microwave transmitter 9 a and a microwave receiver 9 b, and the other nozzle 2 of the pair is provided with a microwave transmitter 9 a,
The other nozzle 2 is provided with a microwave receiver 9b.

FIG. 2 shows a case where two pairs of nozzles 2 are provided to face each other at the same level. In this case, if the microwaves have the same frequency, interference may occur, so different frequencies are used. Note that the smaller the pitch in the height direction of the nozzle 2 shown in FIG. 1 is, the higher the level detection accuracy is. However, in the case of the same frequency, there is a risk of interference.
Separate them. Note that a pair of nozzles may be used instead of two pairs.

In FIG. 3, the nozzle 2 is attached in communication with the scrap preheating tank 1, and an air purge nozzle 2a is attached to the nozzle 2 at an angle. An openable and closable flange 4 is attached to the tip of the nozzle 2. The opening / closing flange 4 is a flange 4a attached to the tip of the nozzle.
And flange 4 connected to this flange 4a by hinge 6
b between the flanges 4a and 4b.
The seal plate 3 is provided to seal the entry of the first and second flanges 4a and 4b.
Is fixed. The seal plate 3 is made of a material that does not hinder the transmission of microwaves, for example, Teflon.

A short pipe 7 is connected to the flange 4b, and a flange 8 for supporting one end of the vibration damper 10 is provided at the tip.
a is attached. The other end of the vibration damper 10 is attached to the flange 8b. A gap of several mm is provided between the flange 8b and the tip of the short pipe 7, and the flange 8b is vibrated by vibration.
b is kept out of contact with the short tube 7 and the gap is made small so that microwaves do not leak outside. A sensor 9 is provided on a surface of the flange 8b opposite to the short pipe 7. The sensor 9 is a microwave transmitter 9a or a microwave receiver 9b. The anti-vibration damper 10 is made of rubber, and is provided to protect the sensor 9 from the impact of the scrap 21 input, and determines the characteristics according to the frequency in the three-dimensional direction. Nozzle 2, short pipe 7, flange 4a, 4
b, 8a, and 8b are made of metal so that there is no external divergence of microwaves. Also, the inner surface of the nozzle 2 is made smooth,
The dust 20 is hard to adhere.

Air is supplied from the air purge system 17 to the air purge nozzle 2a. Compressed air from a compressed air source 16 is controlled on / off by a solenoid valve 12 via a receiver tank 14, and is supplied to an air purge nozzle 2a by a flexible hose 11 to absorb the above-mentioned impact. A bypass line is provided at both ends of the solenoid valve 12, and a bypass amount is determined by the needle valve 13. Solenoid valve 1
2 is on / off controlled by the controller 15. Note that compressed air is also supplied from the receiver tank 14 to the other nozzles 2.

In the air purging by the air purging system 17, a "high-speed purging" in which the flow rate 18 in the nozzle intermittently jets at a high speed of 10 m / sec or more, and the needle valve 13 is adjusted so that a small amount of air (gas) flows in the nozzle. 18 is 1
A "low-speed purge" of continuously blowing at 2 m / sec is used. In the high-speed purge, fine scrap 21 and accumulated dust 20 that have entered the nozzle 2 are blown into the scrap preheating tank 1 by a jet of air (gas).

As a result of an experiment in which the scrap 21 was put into the nozzle 2, it was found that the air was not blown into the scrap preheating tank 1 unless the air flow rate was 10 m / sec or more. The larger the scrap 21 is, the easier it is to blow off because the acting force due to the wind pressure is large, but if the scrap 21 is small, it is difficult to blow off because the pressure receiving area is small. An experiment was conducted in consideration of the above, and it was found that a flow rate of at least 10 m / sec or more was required. In addition, if the flow velocity is increased, the pressure of the compressed air source 16 is also increased and the equipment cost is also increased. Therefore, it is more cost-effective to suppress the maximum flow velocity to 10 m / sec.

Since the dust 20 is always flying in the scrap preheating tank 1, it is preferable to continuously perform the low-speed purge when the high-speed purge is not performed in order to prevent the dust 20 from entering the scrap preheat tank 1. In contrast, high-speed purging is preferably performed intermittently for the following reason. The scrap 21 does not continuously enter the nozzle 2. The use amount of purge air (gas) increases, and equipment and operating costs rise. The amount of oxygen in the scrap preheating tank 1 increases, causing a problem in the process. Scrap 21 in nozzle 2 and accumulated dust 20
Will blow off only with the fast purge of the first few seconds.

An increase in the amount of oxygen in the scrap preheating tank 1 causes a problem in the process. The scrap preheating tank 1 uses exhaust gas generated from an arc furnace as a preheating gas, and the exhaust gas contains combustible gases such as CO gas and H ₂ gas. Therefore, when air is used for high-speed purging, if the amount is large, combustible gas may be burned. Also, the scrap 21 is partially heated to 80
At a high temperature of 0 to 1200 ° C., it burns or partially melts and fuses with each other to form a large lump in the scrap preheating tank 1, making it difficult to take out the scrap 21.

FIG. 4 shows an example of the operation sequence of the high-speed purge and the low-speed purge. No. 1 to Non nozzle are shown in FIG.
Are assigned to the nozzles 2 in order from the top. As shown in FIG. 2, there are four nozzles 2 of the same level,
It is sufficient to purge each one sequentially. Nozzle 2 of each No
In this example, a pattern in which high-speed purging continues for several seconds and then low-speed purging continues for a long period is defined as one cycle, and this cycle is repeated. Each N
o, the occurrence of high-speed purge is shifted,
, So that high-speed purging is not performed at the same time. Thereby, the capacity of the compressed air source 16 and the receiver tank 14 can be reduced, and at the same time, a large amount of oxygen can be prevented from entering the scrap preheating tank 1.

Although the above embodiment has described the measurement of the level of scrap, the present invention can be applied to the measurement of the level of a granular substance such as a granular substance or a massive substance. Although the air is used as the purge gas, other gases, such as nitrogen gas and argon gas, can be used.

[0030]

As described above, according to the apparatus for detecting the level of a massive substance of the present invention, the following effects can be obtained. Since the inside of the nozzle is constantly purged at a high speed or at a low speed, scrap and dust hardly enter and are discharged even if they enter, so that the level of loose substances such as scrap can be continuously measured. Scraps and dust can be blown off only by intermittently performing high-speed purging for a duration of several seconds. This also reduces the amount of barge air (gas) and reduces equipment and operating costs. Since the purging is performed continuously, there is no accumulation of scraps and dust in the nozzle, so that it is not necessary to remove them as in the prior art. When providing multiple pairs of nozzles and sensors at the same level, or when increasing the measurement accuracy by reducing the nozzle pitch in the vertical direction, changing the frequency of the microwave used for each pair avoids interference and allows accurate level control. Can be measured. By using the low-speed continuous purge together, it is possible to reduce the amount of flying dust entering the nozzle. By providing a seal plate between the nozzle and the sensor, it is possible to prevent scrap and dust from entering the sensor. Maintenance is easy by providing the opening and closing flange. By supporting the sensor with the vibration damper, the life of the sensor can be extended. Unlike the mechanical type shown in FIGS. 8 and 9, there is no need to evacuate at the time of throwing in the scrap, and there is no entanglement of the weight into the scrap.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement of a level detection device of the present invention in a vertical direction.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a diagram showing a configuration of a level detection device of the present invention.

FIG. 4 is a diagram showing an air purge sequence of the embodiment.

FIG. 5 is a diagram showing an arrangement of a conventional level measurement device in a vertical direction.

FIG. 6 is a sectional view taken along the line X in FIG. 5;

7 is a sectional view taken along the line X in FIG. 5 and is another example different from FIG. 6;

FIG. 8 is a diagram showing a configuration of a conventional mechanical level measurement device.

FIG. 9 is a diagram showing a configuration of another conventional mechanical level measurement device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scrap preheating tank 2 Nozzle 2a Air purge nozzle 3 Seal plate 4 Opening / closing flange 4a, 4b flange 5 Stopper 6 Hinge 7 Short tube 8a, 8b Flange 9 Sensor 9a Microwave transmitter 9b Microwave receiver 10 Vibration damper 11 Flexible hose Reference Signs List 12 solenoid valve 13 needle valve 14 receiver tank 15 controller 16 compressed air source 17 air purge system 18 nozzle flow velocity 20 dust 21 scrap 22 hopper 23 preheating gas 50 sensor mounting flange 51 seal plate 60 sounding device 61 wire 62 weight 63 chamber 64 truck

Claims (3)

[Claims] 1. A level detecting device for detecting a loading height of a granular or massive substance loaded in a storage tank, wherein one or more pairs are provided at opposing positions on the same horizontal plane of the storage tank, and a plurality of pairs are provided in the tank vertical direction. Nozzles are arranged in pairs over the stages, one of the pair of nozzles is provided with a transmitter of a microwave level detection sensor, and the other is provided with a receiver, and air or air is provided between the sensor of each nozzle and the storage tank. A purge system for blowing active gas is provided. The purge system uses a high-speed purge in which the flow rate in the nozzle is high and a low-speed purge in which the flow rate in the nozzle is low. When there are two or more pairs of microwave level detection sensors arranged on the same horizontal plane, different microwave frequencies are used. Detection device. 2. A pair of nozzles are provided with two flanges at the outer end of the tank, between which a seal plate for blocking passage of a substance in the tank is detachably attached. 2. The level detecting apparatus according to claim 1, wherein the transmitter or the receiver is provided via an anti-vibration damper. 3. The high-speed purge in the purge system is 1
0 m / sec or more, low-speed purge is less than 10 m / sec,
Desirably, it is set to 1 to 2 m / sec or more, low-speed purge is performed continuously with all nozzles, and high-speed purge is performed with nozzle 1
3. The level detecting apparatus according to claim 1, wherein purging is performed periodically for a certain period of time for each unit or for one or a plurality of groups.