JPS635673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for early detection of electrode abnormalities in a vertical electric distillation furnace for zinc smelting, and in particular to a method for early detection of electrode abnormalities in a vertical electric distillation furnace for zinc smelting. Concerning methods for early detection of abnormalities.

BACKGROUND OF THE INVENTION In nonferrous smelting, electric distillation furnaces are used for several metals, typified by zinc. Taking a vertical electric distillation furnace for zinc smelting as an example, sintered lumps of oxidized and roasted zinc sulfide ore and coke are charged from the top of the furnace. Coke and zinc oxide react in the high temperature section of the furnace, and the zinc oxide is reduced to zinc vapor. Zinc vapor is drawn from the middle of the furnace and condensed in a condenser. After the zinc has volatilized, the residue descends through the furnace and is discharged from the bottom of the furnace by a rotating scavenger pan. The furnace has 6 to
Nine upper electrodes and the same number of lower electrodes or a single lower electrode placed in the center of the ore dumping pan are provided to generate the required amount of heat using the resistive heat of the charge.

One of the problems in many electric furnaces for smelting, including the vertical electric distillation furnace for zinc smelting as described above, is an abnormality in the upper electrode. The upper electrodes are inserted from outside the furnace into the furnace contents at appropriate intervals along the periphery of the furnace. Each of the upper electrodes, which are generally carbon electrodes, wears out from the tip over time of operation.
Further, since the carbon electrode insertion portion is loaded with charged material at high temperature, electrode breakage is likely to occur.

When abnormalities such as wear and breakage of the upper electrode occur, the following situation occurs.

(b) The brick directly below the electrode is damaged and the seal becomes defective.
As a result, free air enters from around the electrodes, further causing oxidation and consumption of the electrodes.

(b) Damage to the bricks directly under the electrodes causes uneven distribution of contents in the furnace. That is, a large amount of coke is distributed near the furnace wall, and the current is concentrated there, so that the temperature of the furnace wall increases. This increases dissipated heat and reduces the thermal efficiency of the furnace.

(c) Continuing to apply electricity in a broken state will damage the vapor ring bricks, and in severe cases, they may fall off. If it falls off, the vapor ring will be blocked by the contents inside the furnace (coke, sinter), making it impossible to operate.

As a result of the above, the life of the furnace is shortened and the cost of furnace repair increases.

For this reason, we can detect furnace abnormalities early and adjust the electrode position by pushing the electrodes in before electrode wear progresses beyond the allowable limit, and if an electrode breakage accident occurs, immediately stop the power supply and take recovery measures. There is a need to teach.

Conventional technology and its problems Conventionally, the detection of abnormalities in the upper electrode has mainly relied on patrol monitors discovering reddening of the electrode or blowing out of furnace gas during their patrols (2 to 3 times per direction). Even if instruments were used, the only thing that was done was to continuously measure and record the temperature of the furnace wall next to the electrode (chart) and issue an alarm if the upper limit was exceeded.

The following drawbacks are recognized in these conventional methods: (a) (8 hours) Discovery is often delayed after 2 to 3 rounds. Increasing patrols requires manpower.

(b) With conventional furnace wall temperature monitoring methods, an alarm is not issued until the upper limit value (for example, 800°C) is exceeded after a breakage occurs. If the upper limit is lowered, an alarm will often be issued even if there is no abnormality depending on the electrode.

(c) In order to detect a rise in furnace wall temperature due to breakage more quickly, the conventional method requires constant monitoring of the chart, but this is difficult due to the workload of the controller.

Summary of the Invention In view of the problems described above, the inventor of the present invention came up with the idea of applying a personal computer to early detection of electrode abnormalities, and after repeated studies, succeeded in developing a new system.

There are many such electric furnaces in the factory,
Since a large number of upper electrodes are provided per base, the total number of upper electrodes is large. Therefore,
An attempt was made to develop a system that would accurately detect rapid temperature rises in the lower furnace wall of each upper electrode in a short period of time and issue accurate warnings.

In order to perform a moderately detailed abnormality judgment, we have created a "minor failure"
Two types of abnormality settings, called "and""majorfailure", are made, and these are performed through absolute comparison and comparison over time. An absolute comparison is a comparison between the current temperature (T) and the maximum allowable temperature (Tm). Comparison over time is a comparison between the current temperature (T) and the measured temperature (Tn) a predetermined time ago, and determines whether the current temperature is above or below a certain set temperature (Ts) and whether it is a major failure or a minor failure. Very appropriate electrode abnormality monitoring can be performed by providing a difference in the judgment temperature difference. These can be summarized as follows.

1 Absolute comparison If the current temperature (T) exceeds the maximum temperature (Tm), a "serious failure" is displayed. 2 Comparison over time 2.1 If the current temperature (T) is below the set temperature (Ts), the temperature difference (△T = T - Tn ) exceeds A℃..."Serious failure" is displayed.Over B℃ and below A℃..."Minor failure" is displayed below B℃...No abnormality 2.2 If the current temperature (T) exceeds the set temperature (Ts), the temperature difference ( △T=T-Tn) exceeds A'℃..."Serious failure" is displayed.Over B'℃ and below A'℃..."Minor failure" is indicated B'℃ or below...No abnormality Set temperature Ts is average operation It is set near the temperature.
By setting A >A' and B >B', when the current temperature exceeds the set temperature, the tolerance limit for the temperature difference for determining major failure and minor failure will be stricter, and management will be performed more closely. Can be done. The current temperature is measured at very short intervals, for example 10 seconds to 2 minutes. In the event of a major failure, appropriate measures will be taken, such as shutting down the reactor power supply and issuing a warning. In the case of a minor failure, appropriate measures such as issuing a warning are taken.

The above judgment process is carried out through a personal computer, and it is also possible to record data for daily reports, display graphs of temperature changes over time for any electrode at any time, and search for data, thereby making furnace management more appropriate. It is possible to aim for

Furthermore, although the above setting temperature is one, more detailed furnace management can be performed by setting a plurality of setting temperatures (Ts ₁ , Ts _{2 .} . . ). In that case, when selecting the severe failure temperature limits (A, A', A''... in order of low temperature range) and light failure temperature limits (B, B', B''... in order of low temperature range) in each temperature range, Tighten judgment criteria. That is, A>A'>
A″…and B>B′>B″….

Thus, the present invention is a method for early detecting an abnormality in the electrodes in the furnace in a vertical electric thermal distillation furnace for zinc smelting, and the method is such that the temperature of the furnace wall near the electrode inserted into the furnace is adjusted at fixed short intervals. a step of determining a serious failure if the current temperature (T) exceeds the maximum temperature (Tm); and a step of determining at least one setting if the current temperature (T) is below the maximum temperature (Tm). The temperature difference between the current temperature (T) and the measured temperature a predetermined time ago (Tn) (△T=T-Tn) in the corresponding temperature range of the temperature range defined by the temperature (Ts ₁ , Ts ₂ ...)
and determining whether the failure is a major failure or a minor failure according to the degree of the failure, and in this case, the higher the temperature of the temperature range, the stricter the criteria for determining whether the failure is a major failure or a minor failure. A method for early detection of electrode abnormality is provided.

DETAILED DESCRIPTION OF THE INVENTION Taking a vertical electrothermal distillation furnace for zinc smelting as an example, FIG. 2 shows a schematic cross-sectional view of the furnace. Six to nine upper electrodes 1 and six to nine lower electrodes 2 are inserted into the furnace. A charge consisting of ore and coke is charged into the furnace through a rotary ore feeder 3, and reacts as it gradually descends to generate zinc vapor. The generated zinc vapor is sucked through the vapor ring 4, while the residue descends further within the furnace and is discharged via the bottom jacket 5 of the furnace lower machine onto a scavenging pan 6, from where it is discharged outside the furnace.

As shown in FIG. 2a, the upper electrodes 1 are inserted obliquely downward in a radial arrangement pattern at equal intervals along the periphery of the furnace. The number of lower electrodes is the same as the number of upper electrodes, and they are inserted approximately horizontally. Top 6 as shown
When the main and lower six electrodes are connected diagonally, AC voltage can be applied almost continuously from 160 to 320V, and the maximum load is on each pole.
1000KW, total 6000KW. For example, the electrode
A carbon electrode with a diameter of 300 mm is used.

Figure 2b shows how one upper electrode is inserted into the furnace. The electrode 1 projects into the furnace contents through a suitable insertion opening 7 formed in the furnace wall brick. The electrode is supported by a holder 8. The tip of this electrode protrusion part wears out and is prone to breakage, and when such an electrode abnormality occurs, the above-mentioned damage to the shield occurs.

The present invention aims to detect such upper electrode abnormalities at an early stage.

According to the invention, a thermocouple 9 is provided for measuring a sudden temperature rise in the vicinity of the electrode, preferably in the furnace wall below the electrode.
is installed for each upper electrode. For example, the thermocouple is 1
The current temperature of the furnace wall (T) is measured at short time intervals such as minutes.
Measure. The measured current temperature can be determined as "major failure" or "light failure" through the above-mentioned absolute comparison and comparison over time.
is input to a personal computer for determination. A flowchart of abnormality determination is shown in FIG.
As can be seen from Figure 1, the following temperature settings were made in this specific example: Current temperature T...Temperature difference measured every minute △T...Comparison with the temperature 8 minutes ago (△T=T
-T8) Maximum temperature...800℃ Set temperature...550℃ (one) Severe failure temperature limit Temperature range below 550℃...30℃ Temperature range from 550 to 800℃...20℃ Minor failure temperature limit Temperature below 550℃ Range...20℃ 550~800℃Temperature range...10℃ From Figure 1, it can be seen that the following abnormality judgments are made in this example: 1. Absolute comparison If the current temperature exceeds 80℃, a major failure occurs. Display 2 Comparison over time 2.1 If the current temperature is 550℃ or less, the temperature difference exceeds 30℃...Serious failure temperature difference exceeds 20℃ and falls below 30℃...Minor failure temperature difference is 20℃ or less...No abnormality 2.2 Currently If the temperature exceeds 550°C, the temperature difference exceeds 20°C...Serious failure temperature difference exceeds 10°C and falls below 20°C...Minor failure temperature difference exceeds 10°C...No abnormality Temperature exceeding set temperature 550°C As a result of making stricter judgments in the lower temperature ranges than in the lower temperature ranges, we were able to implement extremely good temperature control. Further, the set temperatures are set to 550℃ and 650℃, for example, (i) Temperature difference in the 800 to 650℃ temperature range More than 10℃...Major failure 〃 5 to 10℃...Minor failure (ii) Temperature in the 650 to 550℃ temperature range Difference exceeding 20℃...Major failure 〃 10-20℃...Minor failure (iii) Temperature range below 550℃ Temperature difference Over 30℃...Major failure 〃 20-30℃...Minor failure Judgment is made in three temperature ranges. By doing so, more detailed management becomes possible.

In the case of a major failure, the reactor power is shut down and a lamp is displayed, and in the case of a minor failure, only a lamp is displayed, allowing workers to quickly resolve the problem.

Furthermore, in order to be able to adequately manage the furnace, 1. Graph creation Create a graph for any electric furnace and any electrode for any time (CRT and Printer) 2 Data search Search for temperature data for all electrodes at any time (export to Printer) 3 Measurement of arbitrary electrodes at any time Measurement of current temperature of arbitrary electrodes 4 Storage and preservation of data Data collected every 4 minutes is written to the floppy disk every hour. Stored for 24 hours. twenty four
It is erased and rewritten with new data as time passes.

By adding this system, we completed the Electrode Abnormality Determination and Alarm System (CASET).

FIG. 3 is a system configuration diagram, and FIG. 4 is a system flow diagram. Small reactor and large reactor gauge 8
The furnace was operated for 6 months with a total of 51 electrodes, and the furnace was managed very well.

The major features of this system are the use of a data acquisition control unit (Model 3497A) manufactured by YHP (Yokogawa Heuretsu Pack Card) for measuring and controlling the electromotive force of the thermocouple, and the creation of measurement and control software. We used YHP's HP20016S as a disk stop type personal computer with simple input/output management. Also,
Communication between the personal computer and the data acquisition control unit uses the GP-IB standard. In addition, it was decided that the furnace power cut when the temperature of the furnace wall below the electrode rises would first be determined by a personal computer, and then transmitted to the sequencer through the data acquisition control unit to perform furnace power sequence control.

Effect of the invention (1) Operators can respond more quickly when an abnormality occurs.

(2) Daily report creation has become easier. (Before the system was completed, 51 records were recorded from the recorder's analog chart in 2
I browsed through and transcribed the information once and for all. ) (3) Since the timing of electrode pushing has become more appropriate, the frequency of alarms has been reduced and the negative impact on the furnace wall has also been reduced.

(4) Thermocouple abnormality checks have become more accurate through computer processing, making thermocouple maintenance more reliable and improving measurement reliability.

(5) It has been found that, in addition to electrode breakage and wear and tear, the influence of the load height inside the furnace is significant and clear as a cause of temperature rise, so it is expected that this will lead to in-furnace cracking.

[Brief explanation of the drawing]

Figure 1 is a flowchart showing an example of an electrode abnormality determination method, Figure 2 is a schematic cross-sectional view of a vertical electric distillation furnace for zinc smelting, and Figure 2a is the upper electrode arrangement taken from the direction of line A-A in Figure 2. 2b shows a detailed view of the upper electrode insertion situation, FIG. 3 shows a system configuration diagram, and FIG. 4 shows a system flowchart. 1: Upper electrode, 2: Lower electrode, 3: Rotating ore feeder, 4: Vapor ring, 5: Hearth bottom jacket,
6: Ore discharge tray, 7: Insertion port, 8: Holder, 9: Thermocouple.

Claims (1)

[Claims] 1. A method for early detecting abnormalities in the electrodes in the furnace in a vertical electric thermal distillation furnace for zinc smelting, which measures the temperature of the furnace wall near the electrodes inserted into the furnace at regular short intervals. A step of measuring, a step of determining a serious failure if the current temperature (T) exceeds the maximum temperature (Tm), and a step of determining at least one set temperature if the current temperature (T) is below the maximum temperature (Tm). The current temperature (T) and the measured temperature a predetermined time ago (Tn) in the relevant temperature range of the temperature range defined by (Ts ₁ , Ts ₂ ...)
and a step of determining whether a major failure or a minor failure occurs according to the degree of the temperature difference (ΔT=T−Tn) between the A method for early detection of in-furnace electrode abnormality characterized by stricter judgment criteria.