JP5324832B2 - Level measuring method and level measuring apparatus for ash melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce initial cost and running cost and reduce work on the site. <P>SOLUTION: In an ash melting furnace 2, while inert gas G is supplied from a chip of a main electrode 4 provided on a ceiling wall of a furnace body 3 so as to be liftable/lowerable to inside of the furnace body 3, molten objects within the furnace body 3 are molten to form a molten metal layer M and a molten slug layer S within the furnace body 3. While the main electrode 4 is lowered, back pressure of the inert gas G supplied to inside of the furnace body 3 is measured, and based on the increase rate of the back pressure, the position of the main electrode 4 when the chip of the main electrode 4 is located on the molten slug face and molten metal face is detected. Based on the position of the main electrode 4 when the molten slug face and molten metal face are detected, the thickness L1 of the molten slug layer S is calculated. By a non-contact type distance meter 14 provided in the furnace body 3, a distance L3 from the distance meter 14 to the molten slug face is measured, and based on the thickness L1 of the molten slug layer S and the measured distance L3, the thickness L2 of the molten metal layer M, that is, a molten metal level ML is calculated. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is mainly used in an ash melting furnace such as a plasma electric melting furnace for melting an incineration residue discharged from a refuse incinerator, a fly ash, a sewage sludge and the like to be melted. The present invention relates to an improvement in the level measuring method and level measuring apparatus of an ash melting furnace that measures the molten slag level and the molten metal level by using a back pressure of an inert gas supplied to the furnace and a non-contact distance meter. Is.

Conventionally, as a method for measuring a molten slag level and a molten metal level in an ash melting furnace, for example, Japanese Patent Application Laid-Open No. 2003-42428 (Patent Document 1), Japanese Patent Application Laid-Open No. 2001-50528 (Patent Document 2), Japanese Laid-Open Patent Application No. 10-332268 (Patent Document 3), Japanese Patent Application Laid-Open No. 10-9555 (Patent Document 4), Japanese Patent Application Laid-Open No. 8-320111 (Patent Document 5), Japanese Patent Application Laid-Open No. 8-271319 (Patent Document 6). And a technique disclosed in Japanese Patent Laid-Open No. 10-122544 (Patent Document 7) is known.
Further, although not used in an ash melting furnace, as a method for measuring a molten metal level by detecting a change in the back pressure of a gas supplied from a gas pipe, Japanese Patent Laid-Open No. 9-126858 (Patent Document 8). JP-A 63-196820 (Patent Document 9), JP-A 6-588 (Patent Document 10) and JP-A 6-589 (Patent Document 11) are known. .

  That is, in the technique disclosed in Japanese Patent Application Laid-Open No. 2003-42428, the weight of the melting furnace body is continuously detected by the weight detector, and the molten slag layer level and the molten metal layer level are calculated based on the weight detection signal. Based on this, the ash melting furnace is controlled. In Japanese Patent Laid-Open No. 2003-42428, a metal level measurement probe is inserted into the melting furnace body, the metal level measurement probe is inserted into the molten slag layer, and its tip is brought into contact with the molten metal layer. A technique is disclosed in which the thickness of the molten metal layer is calculated and displayed by detecting this with a metal level measuring device.

  The technique disclosed in Japanese Patent Application Laid-Open No. 2001-50528 is a level detection sensor (metal level detector) inserted into the molten metal or a metal level detector (magnetic system or ultrasonic system) provided outside the side wall of the melting furnace body. ) To detect the molten metal level.

  In the technique disclosed in Japanese Patent Laid-Open No. 10-332268, the heating source supply electrode is brought into contact with the furnace bottom to detect the height of the heating source supply electrode at this time, and the gap between the heating source supply electrode and the base metal is detected. The heating source supply electrode is raised while detecting the resistance value or potential difference, and the base metal level is detected from the change in the resistance value or potential difference and the rising distance of the heating source supply electrode.

  In the technique disclosed in Japanese Patent Laid-Open No. 10-9555, a level detection electrode is inserted into an ash melting furnace, the level detection electrode is moved up and down, and the ratio of voltage to current changes discontinuously in the process. The level of the molten slag and the molten metal is detected by detecting the position of the working electrode.

  In the technique disclosed in Japanese Patent Laid-Open No. 8-320111, the detection member (detection electrode) or the plasma generation electrode is lowered and brought into contact with the surface of the molten slag, and the detection member (detection electrode) or the plasma generation electrode and the base metal The thickness of the molten slag layer is detected to detect the base metal level, or a conductive member that can come into contact with the base metal is provided near the level of the discharged metal surface of the metal. The position of the base metal level is detected by detecting the potential difference between the conductive member and the base metal.

  In the technique disclosed in Japanese Patent Laid-Open No. 8-271319, a metal level detection detector made of ceramic having a density intermediate between molten metal and molten slag is inserted into a melting furnace, and the metal level detection detector is melted. The buoyancy received from the metal is detected as a load cell load by the load cell, and the metal level in the melting furnace is detected online from the load cell load.

  In the technique disclosed in Japanese Patent Laid-Open No. 10-122544, a level probe including a slag molten metal level detection electrode and a metal molten metal level detection electrode is inserted into a melting furnace, and the level probe is moved up and down to be resistive or magnetic. The molten metal level is measured.

  In the technique disclosed in Japanese Patent Laid-Open No. 9-126858, a purge pipe is erected in a molten metal in a mold of a continuous casting facility, purge gas is supplied to the purge pipe, and the back pressure is detected by a back pressure detector. Thus, the molten metal level is measured.

  In the technique disclosed in Japanese Patent Laid-Open No. 63-196820, a gas supply pipe from which an inert gas has flowed out from the lower end opening is inserted into the molten metal, and a change in the back pressure of the gas supply pipe is detected by a back pressure detector. By detecting, the molten metal level is measured.

  The technique disclosed in Japanese Patent Laid-Open Nos. 6-588 and 6-589 is a technique in which a bubbler tube is inserted into a molten metal injected into a mold, and the bubbler tube is foamed to position the bubbler tube. In this example, the back pressure and the like in the metal are measured, and the boundary layer level of the molten metal is measured based on the measured back pressure and the like.

However, all of the above-described conventional techniques use a dedicated level measuring device, and those using a metal level measuring probe require the probe to be replaced for each measurement. There was a problem that the initial cost and the running cost of consumables increased significantly.
Furthermore, when replacing the probe for measuring the metal level, there is a problem that requires on-site work such as confirmation of probe attachment.

Japanese Patent Laid-Open No. 2003-42428 JP 2001-50528 A JP 10-332268 A Japanese Patent Laid-Open No. 10-9555 JP-A-8-320111 JP-A-8-271319 Japanese Patent Laid-Open No. 10-122544 JP-A-9-126858 JP-A 63-196820 JP-A-6-588 JP-A-6-589

  The present invention has been made in view of such problems, and an object of the present invention is to reduce the initial cost and the running cost, and to reduce the work at the site, and a method for measuring the level of an ash melting furnace. And providing a level measuring device.

In order to achieve the above object, the invention of claim 1 of the present invention is characterized in that an inert gas is supplied into the furnace body from the tip of the main electrode provided on the ceiling wall of the furnace body so as to be movable up and down. A predetermined voltage is applied between the furnace bottom electrode arranged on the bottom wall of the furnace body to generate a plasma arc between both electrodes, and the melt to be introduced into the furnace body is generated by the heat generated by the plasma arc. In an ash melting furnace that melts to form a molten metal layer and a molten slag layer in the furnace body, the back pressure of the inert gas supplied into the furnace body is measured while lowering the main electrode, and the back pressure is measured. The position of the main electrode when the tip of the main electrode is on the molten slag surface and the molten metal surface is detected from the change in pressure increase rate, and the molten slag is detected from the position of the main electrode when detecting the molten slag surface and molten metal surface. calculating the thickness of the layer, also provided on the ceiling wall of the furnace body The distance from the microwave rangefinder to the molten slag surface measured by microwave rangefinder, for calculating the thickness of the molten metal layer and a measurement distance until said molten slag surface by the thickness and the microwave rangefinder molten slag layer It is characterized by doing so.

The invention of claim 2 of the present invention is arranged on the main electrode and the bottom wall of the furnace body while supplying an inert gas into the furnace body from the front end of the main electrode provided on the ceiling wall of the furnace body so as to be movable up and down. A predetermined voltage is applied between the furnace bottom electrode and a plasma arc is generated between both electrodes, and the material to be melted in the furnace body is melted by the generated heat of the plasma arc to melt into the furnace body. In the level measuring apparatus used in the ash melting furnace in which the metal layer and the molten slag layer are formed, the level measuring apparatus is provided on the ceiling wall of the furnace body so as to be movable up and down, and injects an inert gas from the tip. A main electrode having a hollow hole, a lifting device having a position detection means for detecting a position for supporting the main electrode while moving up and down while supporting the main electrode, and the furnace body through the hollow hole of the main electrode A gas supply device for supplying an inert gas, and an inert gas A back pressure detector that detects pressure, a microwave rangefinder that is installed on the ceiling wall of the furnace body, measures the distance to the molten slag surface, changes in the increase rate of back pressure by the back pressure detector, and Calculation for calculating the thickness of the molten slag layer, the thickness of the molten metal layer, the molten slag level, and the molten metal level from the position of the main electrode detected by the position detecting means and the measured distance to the molten slag surface measured by the microwave rangefinder. It is characterized by comprising the device .

The level measuring method of the ash melting furnace of the present invention measures the back pressure of the inert gas supplied into the furnace while lowering the main electrode while supplying the inert gas into the furnace from the tip of the main electrode. The position of the main electrode when the tip of the main electrode is on the molten slag surface and the molten metal surface is detected from the change in the increase rate of the back pressure, and the position of the main electrode in detecting the molten slag surface and the molten metal surface calculating the thickness of the molten slag layer from, also the distance from the microwave rangefinder to the molten slag surface and measured by the microwave range finder provided on the ceiling wall of the furnace body, microwaves and the thickness of the molten slag layer since according rangefinder and a measured distance to the molten slag surface and to calculate the thickness of the molten metal layer, and eliminating the need for dedicated level measuring device, after which attained a significant reduction in initial cost and running cost, main Work of the work and the mounting confirmation, such as replacement of such probes for Rureberu measurement is not required, thereby labor saving, such as field operations.
Further, the level measurement method for the ash melting furnace of the present invention uses a microwave rangefinder to measure the distance to the molten slag surface, and thus the distance to the molten slag surface is measured. Even in a dust atmosphere, the distance to the molten slag surface can be accurately measured, and the molten slag level can be accurately measured.

The level measuring apparatus for an ash melting furnace of the present invention includes a main electrode having a hollow hole for injecting an inert gas from the tip, and a position detection for supporting the main electrode to move up and down and detecting a position for supporting the main electrode. Elevating device provided with means, gas supply device for supplying inert gas into the furnace body through the hollow hole of the main electrode, back pressure detector for detecting the back pressure of the inert gas, and up to the molten slag surface Microwave distance meter that measures the distance of the surface, the change in the increase rate of the back pressure by the back pressure detector, the position of the main electrode detected by the position detection means of the lifting device and the molten slag surface measured by the microwave distance meter The above method can be suitably implemented because the apparatus includes a calculation device that calculates the thickness of the molten slag layer, the thickness of the molten metal layer, the molten slag level, and the molten metal level from the measurement distance. As a result, by using the level measuring apparatus of the present invention, it is possible to greatly reduce initial costs and running costs, and to save labor such as on-site work.
In addition, the ash melting furnace level measuring device of the present invention uses the main electrode, lifting device and gas supply device of the ash melting furnace, so that the structure of the ash melting furnace is complicated and installation space is required. There is no such thing as becoming.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an ash melting furnace 2 using a level measuring apparatus 1 according to an embodiment of the present invention, and the ash melting furnace 2 is discharged from a waste incinerator that incinerates municipal waste, industrial waste, and the like. It is intended to melt incineration residue, fly ash, sewage sludge and other materials to be melted, and has a plasma electric melting furnace structure.

  That is, as shown in FIG. 1, the ash melting furnace 2 is disposed in a penetrating manner in a furnace body 3 including a ceiling wall, a peripheral wall and a bottom wall (furnace bottom) formed of a refractory and the like, A vertically movable main electrode 4 connected to the cathode of a DC power supply (not shown), a vertically movable start electrode 5 disposed in a penetrating manner on the ceiling wall and connected to one anode of the DC power supply; A furnace bottom electrode 6 made of a conductive refractory, which is disposed over the entire bottom wall and connected to the other anode of the DC power supply device via a current collector, and a lifting device 7 which supports the main electrode 4 so as to be movable up and down; A start electrode lifting device (not shown) for supporting the start electrode 5 so as to be movable up and down, and a gas supply device for supplying an inert gas G such as nitrogen gas into the furnace body 3 through a hollow hole 4a formed in the main electrode 4 8 and provided on the peripheral wall of the furnace body 3, and to-be-melted materials such as incineration residues in the furnace body 3 And the melt feed device 9 for feeding (screw feeder), and a level measuring device 1 and the like for measuring the molten slag level SL and the molten metal level ML.

  In FIG. 1, 10 is formed on the peripheral wall of the furnace main body 3 and overflows the molten slag, 11 is a slag hot water outlet that allows the molten slag to flow down, and 12 is exhaust gas in the furnace main body 3. It is an exhaust gas exhaust port for discharging.

  In the ash melting furnace 2 configured as described above, in order to start the melting treatment of the melted material such as incineration residue and fly ash, first, the main electrode 4 and the start electrode 5 lowered to the start position Is energized to generate a current between the electrodes 4 and 5, thereby melting the material to be melted in the furnace body 3. This is because a non-conductive material to be melted is interposed between the main electrode 4 and the furnace bottom electrode 6, and a plasma arc is generated between the main electrode 4 and the furnace bottom electrode 6 at the start of operation. It is because it is not obtained.

When the melted material in the furnace is melted and the conductivity is increased, the start electrode 5 is raised to the standby position, and a predetermined voltage is applied between the main electrode 4 and the furnace bottom electrode 6 by the DC power supply device. Then, a plasma arc is generated between the electrodes 4 and 6, and the melt to be melted introduced into the furnace body 3 from the melt melt supply device 9 is melted by the heat generated by the plasma arc.
The inside of the furnace body 3 is maintained in a reducing atmosphere in order to reduce the mixing of heavy metals into the molten slag and to prevent the main electrode 4 and the start electrode 5 from being oxidized. Therefore, an inert gas G such as nitrogen gas is continuously supplied from the gas supply device 8 into the furnace body 3 through the hollow holes 4 a formed in the main electrode 4.

  When the material to be melted in the furnace body 3 is sequentially melted by the plasma arc generated between the main electrode 4 and the furnace bottom electrode 6, a molten metal is formed in the furnace body 3. Since this molten metal contains many slag components such as silica and metals such as iron in the melted material such as incineration residue, the molten slag layer S and the molten slag located above due to the difference in specific gravity. It is separated into a molten metal layer M located below the layer S.

The molten slag sequentially overflows from the molten slag tap 10 and falls down into a water-cooled tank (not shown) in which cooling water is stored after flowing down the slag tap 11, where it is cooled with water to form granulated slag. Is done.
Further, the exhaust gas generated in the furnace body 3 is introduced into the combustion chamber (not shown) through the exhaust gas discharge port 12 formed in the ceiling wall by an attracting action of an induction fan (not shown) and burned there. After being purified through an exhaust gas treatment device (not shown) or the like, it is discharged into the atmosphere.

  On the other hand, the molten metal located below the molten slag remains and accumulates in the bottom wall (furnace bottom) sequentially with the lapse of the operation time of the ash melting furnace 2, and the level of the molten metal layer M is raised to increase the molten metal layer M. Increase the thickness of the. Along with this, the thickness of the upper molten slag layer S gradually decreases in combination with the fact that the molten metal volume of the furnace body 3 is constant.

  By the way, when the level of the molten metal layer M rises, the thickness of the molten slag layer S becomes thin and the fluctuation value of the arc voltage and arc current becomes large, and stable operation becomes difficult, and molten metal is added to the molten slag. Since problems such as deterioration of the quality of the slag occur due to mixing and discharging, the level measuring device 1 measures the molten slag level SL and the molten metal level ML and provides them at the lower part of the peripheral wall based on the measurement results. The tapped holes (not shown) are intermittently opened, and the molten metal is extracted therefrom so that the thickness of the molten metal layer M does not exceed a predetermined thickness.

  The level measuring device 1 is provided on the ceiling wall of the furnace body 3 so as to be movable up and down, and supports the main electrode 4 having a hollow hole 4a through which an inert gas G is jetted from the tip, and supports the main electrode 4 to move up and down. The elevating device 7 provided with a position detecting means 7a for detecting the position supporting the main electrode 4, and the gas supply device 8 for supplying the inert gas G into the furnace body 3 through the hollow hole 4a of the main electrode 4. A back pressure detector 13 for detecting the back pressure of the inert gas G, a non-contact type distance meter 14 provided on the ceiling wall of the furnace body 3 for measuring the distance L3 to the molten slag surface, and back pressure detection The thickness L1 of the molten slag layer S from the change in the increase rate of the back pressure by the vessel 13, the position of the main electrode 4 detected by the position detecting means 7a of the lifting device 7 and the measured distance L3 to the molten slag surface measured by the distance meter 14 And the thickness L2 of the molten metal layer M, the molten slurry It comprises an arithmetic unit 15 for calculating the level SL and the molten metal level ML, respectively. The main component is based on the change rate of the back pressure of the inert gas G supplied into the furnace body 3 through the hollow hole 4a of the main electrode 4. The position of the main electrode 4 is detected when the tip of the electrode 4 is on the molten slag surface and the molten metal surface, and the position of the main electrode 4 in the detection of the molten slag surface and the molten metal surface is correlated with the back pressure. Then, the thickness L1 of the molten slag layer S is calculated, and the thickness L2 of the molten metal layer M is calculated from the molten slag level SL measured by the distance meter 14 and the thickness L1 of the molten slag.

  The main electrode 4 is formed in a cylindrical shape by artificial graphite, and has a hollow hole 4 a for supplying an inert gas G such as nitrogen gas into the furnace body 3 at the center thereof. Since the main electrode 4 is gradually consumed and shortened during the operation of the ash melting furnace 2, it has a structure in which a new electrode can be added.

  The lifting device 7 includes a mast 7b erected on or near the furnace body 3, a support arm 7c that is cantilevered by the mast 7b, and an electrode gripping device 7d provided at the tip of the support arm 7c. A drive device (not shown) composed of a fluid pressure cylinder or winch for moving the support arm 7c up and down, and a position detection means 7a composed of a potentiometer or the like for detecting the position of the support arm 7c supporting the main electrode 4. It is configured.

  The gas supply device 8 includes an inert gas generator 8a such as a PSA nitrogen gas production device, an inert gas supply pipe 8b, a pressure reducing valve (not shown), a constant flow valve (not shown), and the like. The active gas G is supplied to the hollow hole 4 a of the main electrode 4 so that the inert gas G can be supplied from the tip of the main electrode 4 into the furnace body 3.

  The back pressure detector 13 is connected to the downstream side of the inert gas supply pipe 8 b that supplies the inert gas G to the main electrode 4, and is supplied into the furnace body 3 through the hollow hole 4 a of the main electrode 4. The back pressure of the inert gas G is detected.

The non-contact type distance meter 14 is provided on the ceiling wall of the furnace body 3 and measures the distance L3 from the distance meter 14 to the molten slag surface. As this non-contact type distance meter 14, a microwave distance meter including an antenna that transmits and receives microwaves, a controller that converts a time from when a microwave is transmitted to when it is received into a distance, and the like is used. Yes.
As the non-contact type distance meter 14, a laser distance meter or an ultrasonic distance meter may be used instead of the microwave distance meter.

  The arithmetic device 15 is configured to detect the thickness L1 of the molten slag layer S based on the detection signal from the position detection means 7a of the elevating device 7, the detection signal from the back pressure detector 13, and the detection signal from the non-contact distance meter 14. The thickness L2, the molten slag level SL, and the molten metal level ML of the molten metal layer M are respectively calculated.

  Next, the case where the molten slag level SL and the molten metal level ML are measured using the level measuring apparatus 1 described above will be described.

As shown in FIG. 2, it is known that when a gas (nitrogen gas) is blown into a liquid (molten slag and molten metal), the back pressure changes according to the specific gravity difference and immersion depth of the liquid.
Therefore, when the main electrode 4 is lowered by the elevating device 7 while the inert gas G (nitrogen gas) is ejected from the tip of the main electrode 4, a gas layer (furnace) is generated due to the difference in specific gravity among the gas in the furnace, the molten slag, and the molten metal. The increasing rate of the back pressure of the inert gas G in the molten slag layer S, the molten slag layer S, and the molten metal layer M is changed. The position of the tip of the main electrode 4 when the increase rate of the back pressure is changed is a boundary surface (a boundary surface between the gas layer and the molten slag layer S, a boundary surface between the molten slag layer S and the molten metal layer M). The distance from the furnace bottom of the furnace body 3 to the molten slag level SL (corresponding to the sum of the thickness L1 of the molten slag layer S and the thickness L2 of the molten metal layer M) and the molten metal level ML (the thickness L2 of the molten metal layer M) Equivalent).

  The measurement procedure is as follows. First, the main electrode 4 is raised by the elevating device 7 until the tip of the main electrode 4 is above the molten slag layer S while the inert gas G is ejected from the tip of the main electrode 4 through the hollow hole 4a. . This is because the change in back pressure is smaller in the gas layer (the space above the molten slag layer S in the furnace body 3) than in the liquid layer (the molten slag layer S and the molten metal layer M), so the main electrode 4 is raised by a certain distance. Confirm that the change in the back pressure is smaller than the set value.

  Next, while the inert gas G is ejected from the tip of the main electrode 4, the main electrode 4 is lowered at a constant speed by the lifting device 7, and the back pressure of the inert gas G is measured by the back pressure detector 13. The position detecting means 7a of the elevating device 7 detects the position of the main electrode 4 when the tip of the main electrode 4 is on the molten slag surface and the molten metal surface from the change in pressure increase rate.

  Therefore, the thickness L1 of the molten slag layer S can be calculated from the moving distance of the main electrode 4 from the molten slag surface to the molten metal surface. The movement distance of the main electrode 4 at this time is obtained by performing arithmetic processing on the detection signal from the back pressure detector 13 and the detection signal from the position detection means 7a by the arithmetic device 15.

  Note that the change point of the increase rate of the back pressure is determined at a point where the change rate of the back pressure (mmAq / sec) exceeds the set value as shown in FIG. In addition, when the raw value of the back pressure varies greatly, it is determined by the rate of change of the moving average value. The number of moving average samples and the moving speed of the main electrode 4 are determined in advance during the trial operation of the ash melting furnace 2.

  By the way, there is a time when the back pressure is not stable immediately after the molten slag surface is determined by the level measuring device 1 when the main electrode 4 is lowered, and the molten metal surface which is the next boundary surface may be erroneously determined at that time. . In that case, after the main electrode 4 is lowered and the molten slag surface is determined, a waiting time is provided when detecting the molten metal surface which is the next boundary surface. That is, the level measuring apparatus 1 is provided with a detection waiting timer (not shown) so that the measurement is performed after the back pressure is stabilized. The waiting time is determined in advance during the trial operation of the ash melting furnace 2.

  The thickness L2 of the molten metal layer M is determined by measuring the distance L3 from the distance meter 14 to the molten slag surface with a non-contact type distance meter 14 and inputting this detection signal to the arithmetic unit 15 where Calculation is performed using the obtained data. That is, the thickness L2 of the molten metal layer M is the molten slag surface measured by the distance meter 14 from the distance L from the distance meter 14 to the furnace bottom of the furnace body 3 (this distance L is constant and measured in advance). Is obtained by subtracting the measurement distance L3 and the thickness L1 of the molten slag layer S.

  The molten slag level SL and the molten metal level ML are obtained by performing arithmetic processing with the arithmetic device 15. That is, the molten slag level SL is obtained by adding the thickness L2 of the molten metal layer M to the thickness L1 of the molten slag layer S, and the molten metal level ML is obtained from the thickness L2 of the molten metal layer M.

It is a schematic longitudinal cross-sectional view of the ash melting furnace using the level measuring apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the position (height) of a main electrode, and the relationship between back pressure. It is a graph which shows the relationship between a main electrode position, nitrogen back pressure, and a nitrogen back pressure change rate.

Explanation of symbols

  1 is a level measuring device, 2 is an ash melting furnace, 3 is a furnace body, 4 is a main electrode, 4a is a hollow hole in the main electrode, 7 is a lifting / lowering device for the main electrode, 8 is a gas supply device, and 13 is a back pressure detector. , 14 is a non-contact type distance meter, 15 is an arithmetic unit, G is an inert gas, L is a distance from the distance meter to the furnace bottom, L1 is a thickness of the molten slag layer, L2 is a thickness of the molten metal layer, and L3 is The distance from the distance meter to the molten slag surface, SL is the molten slag level, ML is the molten metal level, S is the molten slag layer, and M is the molten metal layer.

Claims (2)

While supplying an inert gas into the furnace body from the front end of the main electrode provided on the ceiling wall of the furnace body so as to be movable up and down, a predetermined gap is provided between the main electrode and the furnace bottom electrode disposed on the bottom wall of the furnace body. An ash that generates a plasma arc between both electrodes by applying a voltage, melts the material to be melted in the furnace body by the generated heat of the plasma arc, and forms a molten metal layer and a molten slag layer in the furnace body In the melting furnace, the back pressure of the inert gas supplied into the furnace body is measured while lowering the main electrode, and the main electrode tip is changed to the molten slag surface and the molten metal surface from the change in the increase rate of the back pressure. The thickness of the molten slag layer is calculated from the position of the main electrode at the time of detecting the molten slag surface and the molten metal surface, and the position of the microelectrode provided on the ceiling wall of the furnace body. molten scan from the microwave rangefinders by waves rangefinder Measuring the distance to the grayed surface, the ash melting furnace, characterized in that to calculate the thickness of the molten metal layer and a measurement distance until said molten slag surface by the thickness and the microwave rangefinder molten slag layer Level measurement method. While supplying an inert gas into the furnace body from the front end of the main electrode provided on the ceiling wall of the furnace body so as to be movable up and down, a predetermined gap is provided between the main electrode and the furnace bottom electrode disposed on the bottom wall of the furnace body. A voltage is applied to generate a plasma arc between both electrodes, and the molten material thrown into the furnace body is melted by the generated heat of the plasma arc to form a molten metal layer and a molten slag layer in the furnace body In the level measuring apparatus used in the ash melting furnace, the level measuring apparatus is provided on the ceiling wall of the furnace body so as to be movable up and down, and has a main electrode provided with a hollow hole for injecting an inert gas from the tip, A lifting device provided with position detecting means for detecting a position for supporting the main electrode and detecting a position for supporting the main electrode, and a gas supply device for supplying an inert gas into the furnace body through the hollow hole of the main electrode, , Back pressure detector to detect back pressure of inert gas and Microwave distance meter that is provided on the ceiling wall of the furnace body and measures the distance to the molten slag surface, the change in the increase rate of the back pressure by the back pressure detector, and the position of the main electrode detected by the position detection means of the lifting device And an arithmetic unit that calculates the thickness of the molten slag layer, the thickness of the molten metal layer, the molten slag level, and the molten metal level from the measured distance to the molten slag surface measured by a microwave distance meter, respectively. Level measuring device for ash melting furnace.

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