JPH11201420A - Method of detecting surface level of melt in electric resistance fusion furnace for ash processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate the necessity to provide a current application detector separately, and also, detect the surface level of the melt within an electric resistance fusion furnace for ash processing with accuracy by compensating the influence of the abrasion of the electrode. SOLUTION: In condition that voltage is applied to an upper electrode 1 and an under electrode 3, both electrodes 1 and 3 are brought into contact with each other, and a short circuit is detected, and a pulse counter is reset to zero, and then the upper electrode is raised, and the rise distance of the upper electrode 1 is pulse-counted, and the surface level of the melt is detected by the pulse count position of the upper electrode at the time of the current value having become zero. Moreover, in condition that voltage is applied to the upper electrode 1 and the under electrode 3 after a specified time, both electrodes 1 and 3 are brought into contact with each other, and the short circuit is detected, and the zero reset is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting a surface level of a melt in an electric resistance melting furnace for ash treatment for melting incineration ash and fly ash.

[0002]

2. Description of the Related Art Conventionally, waste such as municipal waste has been incinerated in an incineration facility, and incinerated ash and fly ash generated have been disposed of in landfills. However, due to the problem of groundwater contamination due to elution of harmful heavy metals. A method for melting ash with fuel, electric power, or the like has been proposed, and some of the ash are actually processed. Among them, as a melting furnace of ash processing mainly incinerated ash and fly ash,
An electric resistance melting furnace for ash treatment has been proposed.

FIG. 4 is a schematic view of a conventional electric resistance melting furnace for incineration ash treatment. The electric resistance melting furnace for ash treatment includes an ash input port 4 for incinerated ash or fly ash, an exhaust port 5, a molten metal discharge furnace. An outlet 6, a molten slag discharge port 7, and a molten salt discharge port 8 are provided. The upper electrode 1 which goes up and down by the electrode lifting device 2 from the furnace ceiling is inserted into the electrode, the tip of the upper electrode 1 is immersed in the molten slag layer, and the lower electrode 3 is provided at the furnace bottom. The molten slag layer becomes an electric conductor and melts the ash by Joule heat due to electric resistance. The ash is charged from the ash input port 4 so as to cover the molten slag layer and is melted, and the generated molten metal, molten slag and molten salt are discharged from the respective discharge ports 6, 7, and 8.

[0004] In an electric resistance melting furnace for ash treatment, salts such as sodium chloride and potassium chloride which precipitate on the upper part of the molten slag layer are formed, and the molten salt may damage the electrodes or cause a short circuit of the electrodes. In order to stabilize the operation by controlling the raising and lowering of the upper electrode or controlling the timing of discharging the molten metal, molten slag or molten salt, the molten salt and molten metal in the electric resistance melting furnace for ash treatment The slag level is detected.

[0005] In the electric resistance melting furnace for ash treatment shown in FIG.
An electric current detector 19 in which an electric current detection terminal 18 is accommodated in a heat-resistant insulating tube 17 is moved up and down, and a current value flowing between the terminals is measured by an ammeter 11 based on a difference in electric resistance between molten salt and molten slag. The level is measured.

[0006]

The above-mentioned energization detector is
It is assumed that the absolute level can be measured, the conduction detector does not wear, and there is no measurement disturbance.
However, there are actually the following disadvantages.

[0007] (1) In the energization detector, when the detection unit is normally put in a hot-water state and is attached to slag only at the time of measurement, the temperature of the detection unit is low.
As shown in (a), the slag cools and solidifies so as to surround the detection portion, and the solidified portion 20 becomes an electric resistance, so that correct current measurement cannot be performed, and slag level detection becomes impossible.

(2) When the detecting section is immersed in the molten material at all times, the influence of cooling and solidifying of the slag is reduced, but as shown in FIG. It becomes worn and the error becomes large, and eventually becomes unusable. In addition, since it is necessary to perform measurement at the surface position of the heat-resistant insulating tube according to the principle of measurement, if worn, it is significantly affected and all errors occur.

(3) Even if an attempt is made to correct the worn portion, it is difficult to send out the current-carrying portion because the current-carrying portion is sealed with a heat-resistant insulating tube. Must be replaced. Therefore, the running cost increases.

According to the present invention, there is no need to separately provide an electricity detector, and the surface level of the melt in the electric resistance melting furnace for ash treatment can be accurately detected by correcting the effect of electrode wear. An object of the present invention is to provide a method for detecting a surface level of a melt in an electric resistance melting furnace for ash treatment.

[0011]

According to the method for detecting the surface level of a melt in an electric resistance melting furnace for ash treatment of the present invention, the upper electrode is lowered while a voltage is applied to the upper electrode and the lower electrode. Stop the upper electrode at the position where the electrode and the lower electrode come into contact and a short-circuit current flows to the electrode, reset the pulse counter to zero, raise the upper electrode, pulse-count the rising distance of the upper electrode, and flow to the electrode It is characterized in that the surface level of the melt is detected by a pulse count value when the current value becomes zero.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the principle of detecting the surface level of a melt in an electric resistance melting furnace for ash treatment according to the present invention.

In the electric resistance melting furnace for ash treatment, an upper electrode 1 is provided so as to be able to move up and down by an electrode elevating device 2 and a lower electrode 3 is provided at the furnace bottom, as in the prior art. And the like, an ash input port 4, an exhaust port 5, a molten metal outlet 6, a molten slag outlet 7, and a molten salt outlet 8 are provided.

The upper electrode 1 and the lower electrode 3 are connected to a power transformer 9 for melting electric resistance, and a voltmeter 10 and an ammeter 11 are arranged on the secondary side of the power transformer 9 for melting electric resistance.

The upper electrode 1 is supported by an electrode support arm 12 of the lifting device 2, and the electrode support arm 12 moves up and down a mast 14 by a motor 13. The rotary encoder 15 is directly connected to the rotation axis of the motor 13,
The moving distance of the upper electrode is calculated by 6.

Next, the melt surface level detection of the present invention will be described.

Now, when a voltage is applied to the upper electrode 1 and the lower electrode 3, at a position where the upper electrode 1 and the lower electrode 3 are in contact with each other, as shown in the graph of FIG. If a short-circuit current flows through the electrode 3 and the pulse counter 16 is reset to zero at this position, the moving distance when the upper electrode 1 moves up is counted by the pulse counter 16 so that the upper electrode with the lower electrode 3 as a reference is counted. The moving distance of the electrode 1, that is, the absolute position of the upper electrode 1 can be known.

The upper electrode 1 is lifted, and the upper electrode 1 and the lower electrode 3 are air-insulated at the moment when the upper electrode 1 separates from the melt surface 17 and drains, and as shown in the graph of FIG. It becomes zero. Therefore, the absolute position of the upper electrode 1 when the current value becomes zero becomes the melt surface level.

It is more effective in the following cases to set the pulse count value at the time when the current flows to the melt surface level after the current has been reduced to zero after the draining of the hot water. That is, when the viscosity of the melt is high, the melt is pulled and rises as the electrode rises, so that an error that the apparent level becomes large occurs. The error may be smaller if the electrode is lowered after the surface of the melt is made substantially horizontal and the position where the current flows through the electrode is set to the slag surface level. The lower electrode 3 hardly wears out even if it is operated for several days, but the upper electrode is intensely worn. Therefore, if zero reset is not performed in the process of detecting the level, a detection error increases. Also, since the level does not change suddenly,
Operation can be performed well if measurement and monitoring are performed about once every 15 minutes.

FIG. 2 is an explanatory diagram of the error correction method according to the present invention, and FIG. 3 is a flowchart of the correction according to the present invention.
As shown in (1), when the amount of consumption of the upper electrode 1 is small or small, the moving distance of the upper electrode 1 from the position where it was first reset to zero is counted by a pulse counter, so that the surface level of the melt can be used for the operation. To the extent that it can be detected. However, after that, as shown in FIG. 2B, when the upper electrode 1 is consumed by a length l ₁ ,
When the consumed upper electrode 1 is raised, when the moving distance is counted by the pulse counter from the zero reset position before the consumption, the current value flowing through the electrode in a short moving distance becomes zero, and the counted position becomes the surface level of the molten material. , will be counted only shallow distance l ₃ the length l ₁ from the actual distance l _2, it can not be accurately detected melt surface level.

Therefore, in order to make a correction due to the consumption of the upper electrode 1, when measuring the level, the lowering of the upper electrode 1 is started and lowered until a short-circuit current flows.
After confirming the short-circuit current due to the contact between the upper electrode 1 and the lower electrode 3, the lowering of the upper electrode 1 is stopped, and the pulse counter is reset to zero. After correcting the zero reset position, the upper electrode starts rising, and the pulse count value of the pulse counter when the current value becomes zero becomes the melt surface level.
In addition, when approaching the short-circuit current while the upper electrode is descending, if the descending speed is reduced, the stopping accuracy is improved, and the damage due to the collision between the electrodes and the excessive error can be reduced.

From the above, when the upper electrode and the lower electrode are brought into contact with each other during operation and the pulse counter is reset to zero, the consumption of the upper electrode is corrected.
Even if the upper electrode is exhausted, the surface level of the melt can be accurately detected.

As a method for detecting a state in which the upper electrode and the lower electrode are in contact with each other, the circuit impedance of the electric resistance melting furnace is always the same value without changing due to slag or operating conditions. Can be requested. Since the time when the short-circuit current flows is the time when the upper electrode and the lower electrode are in contact with each other, it may be monitored.

[0024]

According to the present invention, there is no error that occurs when the slag is cooled and solidified in the current-carrying part, and the surface level of the molten material can be detected accurately. In addition, errors caused by electrode wear due to salt can only be corrected by newly resetting to zero.
The surface level of the melt can be accurately detected. Furthermore, the cost required for slag level detection can be kept low.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of detecting the surface level of a melt in an electric resistance melting furnace for ash treatment of the present invention.

FIG. 2 is an explanatory diagram of an error correction method according to the present invention.

FIG. 3 is a flowchart of correction according to the present invention.

FIG. 4 is a schematic view of a conventional electric resistance melting furnace for treating incineration ash.

FIG. 5 is a schematic view of a current detector of a conventional electric resistance melting furnace for treating incineration ash.

[Explanation of symbols]

 1: Upper electrode 2: Electrode lifting device 3: Lower electrode 4: Ash inlet 5: Exhaust outlet 6: Molten metal outlet 7: Molten slag outlet 8: Molten salt outlet 9: Power transformer for melting electric resistance 10: Voltmeter 11: Ammeter 12: Electrode support arm 13: Motor 14: Mast 15: Rotary encoder 16: Pulse counter 17: Heat resistant insulating tube 18: Conduction detection terminal 19: Conduction detector 20: Coagulation unit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Sadaharu Hara 46-59, Nakahara, Tobata-ku, Kitakyushu Nippon Steel Corporation Inside the Engineering Business Unit (72) Inventor Shinji Iwamoto 46-59, Nakahara, Tobata-ku, Kitakyushu Within Steel Plant Design Co., Ltd. (72) Inventor Shuichi Matsumoto 46-59 Ohara Nakahara, Tobata-ku, Kitakyushu City Inside Nippon Steel Plant Design Co., Ltd.

Claims (1)

[Claims] 1. An upper electrode is lowered while a voltage is applied to the upper electrode and the lower electrode, and the upper electrode is stopped at a position where the upper electrode and the lower electrode come into contact with each other and a short-circuit current flows through the electrode. After resetting the counter to zero, raise the upper electrode, pulse count the rising distance of the upper electrode,
A method for detecting a surface level of a melt in an electric resistance melting furnace for ash treatment, wherein the surface level of the melt is detected by a pulse count value when a current value flowing through an electrode becomes zero.