JP5346625B2 - Melting furnace level measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve application to a melting furnace such as a plasma melting furnace for melting materials to be melted such as incineration ash and in particular, to accurately measure a molten material level within the furnace by using a microwave distance meter. <P>SOLUTION: The microwave distance meter 3 is arranged outside a furnace lateral wall 57 of the melting furnace 50, and microwaves are projected toward molten materials (slag S and metal M) within the furnace 50 from the microwave distance meter 3. By measuring the intensity of the reflected waves, it is determined whether or not the molten materials within the furnace 50 are slag layers S or metal layers M. Based on this, the molten material level (slag level SL and metal level ML) is detected. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention is applied to a melting furnace such as a plasma melting furnace that melts a material to be melted such as incinerated ash, and more particularly a melting furnace that measures a melt level (slag level or metal level) using a microwave distance meter . The present invention relates to an improvement of a level measuring device .

  Conventionally, as a method for measuring the melt level of a melting furnace, there is a method in which a probe is directly inserted into the molten metal in the melting furnace, and a method using a back pressure of compressed gas or a magnetic permeability is used. Is known (see Patent Document 1).

  However, in such a case, energization of the melting furnace is stopped at the time of measurement, and batch measurement is performed, so that the number of times of measurement per day is limited. In addition, since a special probe that becomes a consumable is used, the running cost is very high.

By the way, as what measures a melt level using a microwave rangefinder, what was described in patent document 2, for example is known.
This is done by placing a microwave rangefinder above the transport container, projecting the microwave from the microwave distance meter toward the melt in the transport container, and measuring the intensity of the reflected wave. Level and metal level are measured simultaneously.

However, such a device is not used in a melting furnace, and a microwave rangefinder is disposed above the transport container to project the microwave toward the melt. There was a problem.
(1) When the gas layer above the melt is in a high dust atmosphere as in a melting furnace, the reflected wave of the microwave passing there is not stable.
(2) When the gas layer above the melt is in a high dust atmosphere like a melting furnace, a filter is required to prevent dust from entering the antenna of the microwave rangefinder. Makes it difficult to measure for a long period of time. Even when the filter is cleaned, this is difficult during operation of the melting furnace.
(3) Since the microwave is attenuated in the slag layer, the measurement of the metal level is unstable.

  On the other hand, it is also known to measure the consumption of refractory from the furnace side wall using a microwave distance meter (see Patent Document 3).

  However, this is used in melting furnaces but does not measure the melt level in the furnace.

JP 10-122544 A JP 2003-344142 A JP 2003-294430 A

  As described above, none of the conventional devices accurately measure the melt level in the furnace using the microwave rangefinder.

The present invention was devised in view of the above-mentioned problems and was devised to solve this problem. The problem is that a microwave rangefinder can be used to accurately measure the melt level in the furnace. An object of the present invention is to provide a level measuring device for a melting furnace.

The melting furnace level measuring apparatus according to the present invention has a microwave distance meter disposed outside the furnace side wall of the melting furnace, projects microwaves from the microwave distance meter toward the melt in the furnace, and reflects the reflection. It is characterized by determining whether the melt in the furnace is a slag layer or a metal layer by measuring the intensity of the wave, and detecting the melt level based on this.

  A microwave rangefinder is disposed outside the furnace side wall of the melting furnace. In the case of a single microwave rangefinder, for example, the microwave rangefinder is arranged so as to be movable in the vertical direction. And a microwave is projected toward the melt in a furnace from a microwave rangefinder. That is, the microwave from the microwave rangefinder passes through the furnace side wall, reaches the melt in the furnace, and is reflected thereby. The reflected wave then passes through the furnace side wall and reaches the microwave rangefinder. At this time, the intensity of the reflected wave of the microwave changes depending on the melt in the furnace. Therefore, it is determined whether the melt in the furnace is a slag layer or a metal layer based on this change in strength. Detect the metal level that is the boundary of the layer.

  It is preferable to arrange the microwave rangefinder so as to be movable in the vertical direction. In this way, the entire measurement range can be covered by the microwave rangefinder, and the cost can be reduced.

  It is preferable to arrange the microwave rangefinder at the required metal extraction height. In this way, it is possible to detect whether or not the metal level has reached the required metal extraction height, and based on this, it can be used as a guideline for extracting the metal.

  A melting furnace level measuring apparatus according to the present invention is provided on a furnace side wall corresponding to a melt in the furnace and is capable of transmitting microwaves, and is disposed outside the microwave transmitting body to transmit microwaves. It is characterized by comprising a microwave rangefinder that can determine whether the melt in the furnace is a slag layer or a metal layer by projecting and measuring the intensity of the reflected wave.

A microwave transmitting body capable of transmitting microwaves is provided on the furnace side wall corresponding to the melt in the furnace. The microwave rangefinder is disposed outside the microwave transmission body, projects a microwave, and measures the intensity of the reflected wave. Based on the measurement results, it is determined whether the melt in the furnace is a slag layer or a metal layer. Based on this, the melt level, that is, the slag level that is the boundary between the gas layer and the slag layer, or the boundary between the slag layer and the metal layer is determined. The metal level that is is detected.
Since the microwave transmitting body is provided on the furnace side wall, the microwave of the microwave rangefinder can be transmitted and the original function of the furnace side wall is not impaired.

  The furnace side wall includes a refractory that contacts the melt, and a casing that is formed by forming an air-cooled space outside the refractory, and the microwave transmitting body is fitted with a longitudinal slit formed in the casing and a slit. It is preferable to provide a transmission plate that can be worn and transmit microwaves. In this way, it is possible to measure at a continuous height position by arranging the microwave rangefinder outside the microwave transmission body and moving it up and down.

  The furnace side wall includes a refractory in contact with the melt and a casing provided with an air cooling space formed outside the refractory, and the microwave transmitting body penetrates the air cooling space and the casing outside the refractory. It is preferable to provide a plurality of cylindrical nozzles provided at predetermined intervals in the vertical direction. In this way, the microwave distance meter can be measured at intermittent height positions by sequentially arranging the microwave distance meter outside the nozzles of the microwave transmission body.

According to the present invention, the following excellent effects can be achieved.
(1) A microwave rangefinder is placed outside the furnace side wall of the melting furnace, and a microwave is projected from the microwave rangefinder toward the melt in the furnace, and the intensity of the reflected wave is measured. Therefore, it was determined whether the melt in the furnace was a slag layer or a metal layer, and based on this, the melt level was detected, so there was no influence of dust in the furnace, and the reflected wave of microwaves Stabilize. For this reason, the melt level in the furnace can be accurately measured using a microwave distance meter.
(2) Since it is not affected by the dust in the furnace, long-term continuous measurement is possible.
(3) Since the microwave directly reaches the metal layer without passing through the slag layer, the metal layer can be detected reliably.
(4) A microwave rangefinder is placed outside the furnace side wall of the melting furnace, and a microwave is projected from the microwave rangefinder toward the melt in the furnace and the intensity of the reflected wave is measured. Therefore, it is determined whether the melt in the furnace is a slag layer or a metal layer, and based on this, the melt level is detected, so there are no consumables and the running cost can be reduced compared to using a probe. At the same time, continuous measurement is possible without stopping the operation.
(5) Since a microwave distance meter is used, if this is used, the consumption amount of the refractory can be grasped by measuring the thickness of the refractory as in Patent Document 3.

The longitudinal section front view showing the first example of the level measuring device of the melting furnace concerning the present invention. The principal part side view of FIG. The graph which shows the relationship between the distance from a microwave rangefinder, and the intensity | strength of a reflected wave. The longitudinal cross-sectional front view which shows the 2nd example of the level measuring apparatus of the melting furnace which concerns on this invention. The principal part side view of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal front view showing a first example of a level measuring apparatus for a melting furnace according to the present invention. FIG. 2 is a side view of the main part of FIG. FIG. 3 is a graph showing the relationship between the distance from the microwave rangefinder and the intensity of the reflected wave.

  The level measuring apparatus 1 is applied to a melting furnace 50 such as a plasma melting furnace, an arc furnace, an electric resistance furnace, a low frequency induction furnace, a high frequency induction furnace, or the like.

  The melting furnace 50 includes a furnace main body 51, a main electrode 52 provided on the furnace body 51 so as to be movable up and down, a lifting means (not shown) for lifting and lowering the furnace body, a furnace bottom electrode 53 installed on the furnace bottom, It is composed of a melt supply means (not shown) for supplying the melt A such as incineration residue, incineration fly ash and sewage sludge to the furnace body 51, an outlet 54 for discharging slag (molten slag) S, and the like. ing.

  The furnace main body 51 includes a casing (outer shell) 55 and a refractory 56 provided inside thereof. The lower side of the furnace side wall 57 is an air-cooled space 58 between the casing 55 and the refractory 56. Is formed in a so-called air-cooling range, and the upper side of the furnace side wall 57 and the upper wall 59 are formed in a so-called water-cooling range by forming a water-cooling jacket 60 between the casing 55 and the refractory 56. It is designed to withstand slag (about 1500 ° C) and high temperature gas.

  Although not shown, the melt A is stored in a container and continuously charged into the furnace body 51 by melt feed means such as a screw conveyor.

  Although not shown, a DC voltage (200 to 500 V) from a DC power supply (capacity: about 600 to 1000 kWh / t / melted material) is applied between the main electrode 52 and the furnace bottom electrode 53. Therefore, a current flows and a plasma arc is generated. Accordingly, the melt A is heated to 1300 ° C. to 1600 ° C. and sequentially melted.

  When the material to be melted A is melted, the volatile components and carbon are partially oxidized to a gas containing carbon monoxide, while the nonflammable components such as iron and other metals, glass and sand are melted. It becomes a state and becomes a melt. Although not shown, the gas enters the combustion chamber via an outlet duct, where unburned components are completely burned and exhausted from the combustion chamber by the combustion air sent by the combustion air fan. After being cooled, it is led to the chimney through a filter.

  Since the material A to be melted contains silica, alumina, calcia, iron, and the like, when this is melted in the furnace, the slag S (melting slag) S mainly composed of silica, alumina, calcia is upward The metal (molten metal) M mainly composed of iron sinks downward, and a metal layer (molten metal layer) M and a slag layer (molten slag layer) S are sequentially formed and separated from the furnace bottom. Two layers are formed.

Then, the slag layer S continuously overflows from the outlet 54, falls into the slag water cooling tank 61 filled with water, becomes a granulated slag, and is carried out by the carry-out conveyor.
The metal layer M gradually increases in thickness while being accumulated in the furnace bottom. When the layer thickness from the furnace bottom exceeds a predetermined value, at least a part of the metal layer M is discharged from the metal extraction position to the outside of the furnace. Is done.

  The level measuring device 1 is applied to such a melting furnace 50, and is provided on the furnace side wall 57 corresponding to the melted material (slag S and metal M) in the furnace, and is capable of transmitting microwaves. A microwave distance that can be determined whether the melt in the furnace is the slag layer S or the metal layer M by projecting the microwave and measuring the intensity of the reflected wave, arranged outside the microwave transmission body 2 It consists of a total of three.

  The microwave transmission body 2 includes a vertically long slit 4 drilled in a casing 55 and a transmission plate 5 that can be hermetically fitted and transmit microwaves. The slit 4 is vertically elongated in a range in which the boundary height between the slag layer S and the metal layer M of the casing 55 moves, that is, a height range in which the metal level ML can be detected. The transmission plate 5 is made of a material that can transmit microwaves, such as ceramic.

As is well known, the microwave rangefinder 3 includes an antenna (not shown), and transmits microwaves toward the melt as a detection target, and reflects reflected microwaves reflected by the melt. The distance to the melt is measured by receiving with an antenna.
The microwave distance meter 3 is single, and its antenna is applied to the outside of the transmission plate 5 of the microwave transmission body 2 and moved in the vertical direction.

Next, the operation will be described based on such a configuration.
The microwave rangefinder 3 is disposed outside the transmission plate 5 of the microwave transmission body 2 and is moved in the vertical direction, while the microwave is projected and the intensity of the reflected wave is measured. Since the refractory 56 in the measurement path is a derivative, microwaves are transmitted therethrough. Since the slag S and the metal M, which are melts, have different microwave reflectivities, the reflected waves have different intensities.

  FIG. 3 shows an example of the distance from the microwave rangefinder 3 to the melt and the intensity of the reflected wave. The distance from the microwave rangefinder 3 to the slag S or metal M is 500 mm. As shown by the solid line in FIG. 3, the metal layer M reflects most of the microwaves, so the intensity of the reflected wave at 500 mm is high. As shown by the chain line in FIG. 3, the slag layer S transmits part of the microwave, so that there is also a reflected wave after 500 mm.

  For this reason, it is determined whether the measured height position is the slag layer S or the metal layer M depending on the peak value of the intensity of the reflected wave and the presence or absence of the reflected wave after the peak. And the boundary of the slag layer S and the metal layer M is determined, and this is made into the metal level ML.

Next, a second example of the present invention will be described with reference to FIGS.
FIG. 4 is a longitudinal front view showing a second example of the level measuring apparatus for a melting furnace according to the present invention. FIG. 5 is a side view of the main part of FIG.

In the second example, the microwave transmission body 2 is different from the first example.
That is, the microwave transmission body 2 is configured by a plurality of cylindrical nozzles 6 that are provided at predetermined intervals in the vertical direction through the air cooling space 58 and the casing 55 outside the refractory 56. A plurality of nozzles 6 are provided in a range in which the boundary height between the slag layer S and the metal layer M moves, that is, in a height range in which the metal level ML can be detected. Arranged in a staggered pattern. The nozzle 6 includes a cylindrical pipe and a flange attached to the outside thereof.

  Thus, the microwave rangefinder 3 is single and movable so that it can be measured from all the nozzles 6. Of the plurality of nozzles 6, it is desirable to close the ones where the microwave distance meter 3 is not disposed as appropriate.

In this example, while the microwave distance meter 3 is moved between the nozzle bases 6 of the microwave transmission body 2, the microwave is projected by the microwave distance meter 3 arranged in each nozzle base 6, and The intensity of the reflected wave is measured, and it is determined whether the measured height of the nozzle 6 is the slag layer S or the metal layer M. And the boundary of the slag layer S and the metal layer M is determined, and this is made into the metal level ML.
In this example, the measurement is intermittent, but the metal level ML can be more accurately limited by increasing the number of nozzles 6.

Next, a third example of the present invention will be described.
In the third example, although not shown, a single microwave rangefinder 3 is arranged at the required metal extraction height.
In this example, for example, a single nozzle 6 of the microwave transmission body 2 is installed at a required metal extraction height, and the microwave rangefinder 3 is installed in the nozzle 6. Instead of the nozzle 6, the slit 4 and the transmission plate 5 may be provided as in the first example.
In this way, when the microwave is projected from the microwave rangefinder 3 and the intensity of the reflected wave is constantly measured, whether the measured height is the slag layer S or the metal layer M depending on the change in the intensity of the reflected wave. I can judge. Based on this, it can be used as a guide for the timing of extracting the metal M.

Next, a fourth example of the present invention will be described.
Although the fourth example is omitted, the microwave transmission body 2 is provided in a range in which the boundary height between the slag layer S and the gas layer G on the slag layer S moves, that is, a range in which the slag level SL can be measured. .

  In such a case, the microwave from the microwave rangefinder 3 is almost transmitted through the gas layer G. For this reason, since the intensity of the reflected wave of the slag layer S and the gas layer G is different, the slag level SL that is the boundary between them can be constantly measured.

Therefore, the abnormal rise of the slag S can be monitored, and the slag S can be used for operation control of the device following the outlet 54 and control of the ash supply amount and the electric energy.
Further, when the metal level ML is calculated using the measurement result of the slag level SL, the slag level SL can be measured more accurately.

In the above example, the microwave transmission body 2 is composed of the slit 4 and the transmission plate 5 and the nozzle 6. However, the microwave transmission body 2 is not limited to this and can be appropriately changed.
Although the microwave distance meter 3 is single in the previous example, it is not limited to this, and may be plural, for example. In this way, there is no need to move, so there are advantages such as fewer failures.

  The present invention can be used not only for an ash melting furnace such as a plasma melting furnace, but also for a melting furnace (a glass melting furnace, a steelmaking blast furnace) having a molten metal (melt).

  DESCRIPTION OF SYMBOLS 1 ... Level measuring apparatus, 2 ... Microwave transmission body, 3 ... Microwave distance meter, 4 ... Slit, 5 ... Transmission plate, 6 ... Pipe base, 50 ... Melting furnace, 51 ... Furnace main body, 52 ... Main electrode, 53 ... Furnace bottom electrode, 54 ... Outlet, 55 ... Casing, 56 ... Refractory, 57 ... Furnace side wall, 58 ... Air cooling space, 59 ... Furnace wall, 60 ... Water cooling jacket, 61 ... Slag water tank, A ... Molten material , S ... slag layer (slag), M ... metal layer (metal), G ... gas layer, SL ... slag level, ML ... metal level.

Claims (2)

A microwave transmitting body that is provided on the furnace side wall of the melting furnace including a refractory that is in contact with the melt in the furnace and a casing that is provided outside the refractory to form an air cooling space; A microwave rangefinder, which is placed outside the microwave transmission body and can determine whether the melt in the furnace is a slag layer or a metal layer by projecting the microwave and measuring the intensity of the reflected wave. In the melting furnace level measuring apparatus configured as described above, the microwave transmitting body includes a vertically long slit formed in the casing, and a transmission plate that is fitted in the slit and can transmit the microwave. A melting furnace level measuring device. A microwave transmitting body that is provided on the furnace side wall of the melting furnace including a refractory that is in contact with the melt in the furnace and a casing that is provided outside the refractory to form an air cooling space; A microwave rangefinder, which is placed outside the microwave transmission body and can determine whether the melt in the furnace is a slag layer or a metal layer by projecting the microwave and measuring the intensity of the reflected wave. In the melting furnace level measuring apparatus configured as described above, the microwave transmitting body includes a plurality of cylindrical nozzles provided at predetermined intervals in the vertical direction through the air cooling space and the casing outside the refractory. An apparatus for measuring a level of a melting furnace, comprising:

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