JPH01234530A - Automatically controlled melting furnace - Google Patents

Abstract

PURPOSE:To prevent the hanging in a melting furnace by monitoring the combustion state at all times, subjecting the brightness of the video to pattern recognition, converting the same to an electric signal and feeding the signal back to burner combustion pressure control. CONSTITUTION:One terminal of an image fiber 1 such as optical fiber is set in the peep window of respective burners of respective zones A-C and an automatic combustion state monitor device 3 is mounted to the other terminal so that the video signal is converted to the electric signal. The visual field of the peep window brightens when the hanging begins to arise and there is no fall of materials. The electric signals are classified to several stages by the area ratios of brightness and darkness and these signals are fed back to control valves for controlling the combustion pressure, etc. The results of the residual hydrogen quantity by the monitor in a combustion atmosphere measuring and adjusting device 5 are fed back to the orifice control mechanisms near the burners to adjust the combustion atmosphere. The quantity of the molten metal in a holding furnace is known from the signal of a tilting angle 6 and is sent to an automatic combustion pressure control device 4 by which the quantity is compared with a reference value and the combustion pressure is increased or decreased.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in continuous metal melting furnaces.

For more details, electrolytic copper or continuous melting T! This relates to an automatically controlled melting furnace that is an automatic R11l Ill shift melting furnace manufactured by A'5ARCO in the United States, which is known as E equipment.

[Conventional technology]

Conventionally, this type of metal melting furnace has been constructed as shown in FIGS. 3, 4, and 5. In FIG. 4, air is pressurized by a blower or the like and heated by an air heater (air preheater). On the other hand, liquefied petroleum gas such as butane gas or combustible gas such as natural gas is heated by exchanging heat with the heated air, and is sent to each burner where it is mixed with the heated air and combusted.

Each burner is divided into three burner groups, A zone, B zone, and C zone from the bottom as shown in the cross-sectional elevation view of Figure 3. In each zone, the pressure is equalized by a donut-shaped manifold surrounding the shaft. As shown in Fig. 6 in the form of a plan view, the air flows into seven locations in zone A, B, and C.
The fuel 1'31 gas is fed into the furnace from eight zones, and the fuel 1'31 gas is sucked in from the side through orifices as shown in FIG.

Combustion control at this time is performed by so-called combustion pressure, which is obtained by converting the outflow of gas and outflow of air in each zone into pressure.

On the contrary, since the condition of the charge material O 1 is not uniform, even if the manifold is designed to maintain almost equal combustion pressure all around the circumference of the shaft furnace, it tends to melt in certain places in the circumferential direction, and in some places it melts easily. This may cause so-called overhang, which is difficult to melt, and may make it impossible to continue operation. To prevent this, in order to prevent this, when the shelf hanging is completed, each burner cannot be controlled independently in the circumferential direction of the shift furnace, so the combustion pressure of each zone is adjusted as a whole using the manual. The work is done manually. 1. This shelf hanging phenomenon was detected by visually monitoring the inside of the furnace through a combustion status monitoring window at one end of the burner, and was manually adjusted.

In order to perform stable casting, it is desirable for a constant amount of hot metal to flow out of the melting furnace, but this adjustment is also possible by checking the amount of hot metal in a holding furnace with an inclined shaft that temporarily stores the hot metal that flows out of the melting furnace. When the combustion pressure is high or low, the combustion pressure is manually lowered or raised depending on the situation.

In addition, electrolytic copper, etc. introduced from the upper charging port of the shaft furnace,
It is necessary to operate the burner in a slightly reducing atmosphere so that it dissolves with little oxidation. The combustion atmosphere of each burner is controlled by the preheated air outflow and gas flow rate, but major adjustments are made by the differential pressure between the preheated air combustion pressure and the gas combustion pressure, and fine adjustments are made manually by adjusting the orifice of the gas piping near the burner. The opening degree is adjusted using a screwdriver, and compliance is checked by monitoring the amount of residual hydrogen in the combustion exhaust gas.

[Problem that the invention attempts to solve]

Since the phenomenon of shelving of charged material is detected visually through the monitoring window at one end of the burner, it is possible to prevent variations in manual judgment, delays in detection, and to control each burner independently in the circumferential direction of the shaft furnace. Due to reasons such as (1) and (1), it was not possible to avoid the shelf-hanging phenomenon, which caused discontinuous melting.

Furthermore, since combustion monitoring is work that requires a lot of use of the eyes, it is undesirable from the safety and health standpoint of the workers, and since the work involves hot work near the burner, it is also undesirable as a working environment.

The amount of hot water was also adjusted manually, so variations due to manual labor were unavoidable.

Also, fine adjustments to the combustion atmosphere were done manually, so
The problem was that the fluctuations in the concentration of hydrogen or carbon monoxide in the combustion atmosphere became large, and the fluctuations in the amount of oxygen in the molten steel became large, causing quality deterioration of the casting.

The purpose of the present invention is to prevent the shelf-hanging phenomenon in the melting furnace, eliminate fluctuations in the amount of melt and therefore the amount of hot water in the holding furnace, thereby enabling stable casting, and furthermore, making it possible to finely adjust the ratio of the gas flow rate to the air flow rate. By automating this process, we aim to stabilize the quality of castings by reducing the fluctuations in reducing gas in the combustion atmosphere and the fluctuations in the amount of oxygen in molten steel, and also reduce the amount of fluctuation in reducing gas in the combustion atmosphere and the fluctuation in the amount of oxygen in molten steel. The purpose is to free workers from

[Means to solve the problem]

The present inventors conducted tax consideration research in order to solve the problem of face writing. As a result, a combustion status monitoring device was installed in the combustion status monitoring window near the burner, and the video signals sent from the device were classified into patterns based on the area ratio of brightness and darkness, and converted into signals.
By controlling the combustion pressure, shelf suspension is prevented, and the amount of hot water in the holding furnace that stores the melted material outside the melting furnace and the tendency of increase or decrease in the amount of hot water are detected by the tilt angle of the furnace, and the combustion pressure is controlled for melting. We have completed the present invention by discovering that it is possible to reduce fluctuations in the reducing gas in the melting furnace by stabilizing the amount, automatically analyzing the combustion atmosphere, and automatically adjusting the fuel-air ratio.

That is, the present invention provides a combustion state monitoring device, a means for transmitting a video signal generated by the device, a device for electrically pattern-recognizing the signal and converting it into a signal, and a burner combustion pressure control device for converting the converted signal into a signal. a means of providing feedback and communication to
This is an automatically controlled melting furnace configured to have a combustion pressure control device for a burner and a burner connected in series, and to automatically control combustion in the furnace by the connected device.

Optical fiber is preferable as a means for transmitting the video signal generated by the combustion state monitoring device.

In addition, in a melting furnace in which a tiltable melt holding furnace is installed outside the melting furnace, the holding furnace tilting angle detection device, the tilting angle, and an increase/decrease trend signal of the tilting angle are sent to the burner combustion pressure control device. A means for feedback and transmission, and a combustion pressure control device for the burner are connected, and the connected device automatically controls the amount of hot water in the holding furnace and the tendency of increase/decrease in the amount of hot water in the melting furnace. The above-mentioned automatically controlled melting furnace is configured as follows.

1) A device for zumbling the combustion atmosphere, a device for automatically analyzing the gas, and a device for automatically adjusting the combustion-air ratio based on the signal of the amount of reducing gas in the gas are installed in series, and the device is connected to the device. The above-mentioned automatically controlled melting furnace is configured to automatically adjust the degree of reduction of the combustion atmosphere.It is more preferable if the three automatic control devices described above are incorporated.

The combustion state monitoring device sends the images inside the furnace as video signals to the combustion controller, which classifies the video signals into patterns based on the area ratio of light and dark, converts them into electrical or pneumatic signals, and controls the gas flow 8. Control the air flow rate. The video signal from the monitoring device can be sent as an electrical signal by using a large number of photocells in the monitoring device, but it is also possible to send the video signal to the combustion controller using an optical fiber, where the pattern is recognized electrically. However, -5 is more preferable as there is less noise. Normally, gas flow rate and air flow rate are each expressed in terms of gas pressure, so this will be referred to as combustion pressure hereafter.

Conventional manual combustion pressure control for each manifold in each zone does not quickly eliminate shelf hanging, so it is most preferable to control combustion pressure for each burner, but it also increases equipment costs, so the circumference should be divided into at least three parts. For example, A.G.22
It is preferable to control the combustion pressure by dividing the combustion pressure into three or more zones for each zone, such as main + 3 + 2, B zone 3 + 2 + 3, and C zone 3 - 3 - 2. However, if each zone is divided into two or less, it will be difficult to quickly eliminate the hanging problem, which is not preferable.

FIG. 1 shows an outline of the automatic control device of the present invention.

1 is an image fiber made of glass fiber, one end of which is inserted into the viewing window of each burner in each zone, and the other end (3) is an automatic combustion status monitoring device that converts video signals into electrical signals. The IJ has been investigated.

The field of view through the viewing window becomes bright when shelf suspension is about to occur and there is no material falling; conversely, the brightness decreases when undissolved matter is blocked, and in a steady state it shows an intermediate brightness. The electrical signals are classified into several levels depending on the ratio of bright and dark areas, and the signals are fed back to mechanisms such as control valves that control combustion pressure.

5 is a combustion atmosphere measuring and adjusting device, which is a combustion atmosphere III
I-air control is automatically controlled by adjusting the orifice control mechanism near the burner by feeding back the results of the residual hydrogen amount monitored.

Furthermore, the amount of hot water in the holding furnace provided at the outlet of the shaft furnace is also a factor in controlling the overall combustion pressure. The amount of hot water is known from the holding furnace tilt angle 6 converted into an electric or pneumatic signal, which is sent to the combustion pressure automatic control device 4, and the difference from the reference value is sent to 7 as a signal. When the amount of hot water is less than the standard amount, the overall combustion pressure is automatically increased, and when it is more than the standard amount, the overall combustion pressure is decreased.

In addition, even when the amount of hot water is less than the same standard amount, the overall combustion pressure is controlled by separately detecting when it is decreasing and when it is increasing.

9 is a gas generator for gasifying liquefied gas, and 8 is a heat exchanger between the gas and heated air.

Figure 2 shows the control system. Until the intermediate automatic control start-up point, the furnace exhibits an unsteady state from the start of combustion.
The part below the broken line shows the automatic control system of the present invention. Among these, for combustion pressure control, it is preferable that the combustion state monitoring information is given priority in the remaining unsteady state of dry firing or melting, and that the holding furnace storage 1ffl change information is activated when each burner is in a steady state. .

Table 1 below shows an example of an algorithm for combustion pressure control.

[Examples] The present invention will be specifically explained below using Examples, but the present invention is not limited in any way by the Examples.

(Example 1) In the shirt 1~furnace equipped with 7 burners, 8 burners, and 8 burners with a combustion capacity of 1.8 million kcal/hr in zones A, B, and C3, respectively, the combustion pressure rank was set to 2. The control mechanism is divided as shown in the table and allows the combustion pressure of each burner to be changed independently.

The settings are made in the order shown in Figure 2, Combustion Plan]] - Jar 1 -, and combustion is performed according to the images of the image fiber that come in every 3 minutes and the electrical signal of the amount of hot water stored in the holding furnace that comes in every 5 minutes. The pressure was automatically controlled, and the orifice opening of the burner gas piping was automatically controlled based on information on the amount of residual hydrogen in the mixture combustion exhaust gas to achieve optimal combustion conditions.

Combustion pressure control was given priority to dry firing or melting in the remaining unsteady state, and when each burner was in a steady state, combustion pressure was controlled by changing the amount of hot water stored in the holding furnace.

When electrolytic copper was melted at a rate of 45 t/hr in this manner, completely automatically controlled operation was possible with only human operations required during initial settings and shutdown.

(Example 2) In Example 1, A, B, and C3 zones are each divided into three parts, A zone 2 + 3 + 3 B zone 3 + 2 + 3 C zone 3 + 3 + 2 parts - bracket As a result of control, the hanging state can be avoided,
The same effects as in Example 1 were obtained.

〔Effect of the invention〕

The combustion status is constantly monitored using optical fiber, the brightness of the image is recognized as a pattern, this is converted into an electrical signal, and the signal is fed back to the burner combustion pressure control, so there is no need for manual adjustments and the phenomenon of stockpiling is eliminated. Almost gone.

In addition, since the holding furnace water flow rate is incorporated into this control and fed back into the burner combustion pressure control, stable casting is possible with almost no fluctuation in the holding furnace water flow.

By stabilizing the melting, fluctuations in temperature and the amount of oxygen in the molten steel were reduced, and the quality of the casting was stabilized.

Furthermore, since the opening degree of the orifice for fine adjustment of gas flow rate is automatically controlled according to the amount of reducing gas in the combustion gas, fluctuations in the combustion atmosphere or CO concentration are reduced, improving the quality of the castings. Even more stable.

It also freed workers from the visually demanding task of monitoring combustion. Furthermore, since the workers were freed from the heat work in the vicinity of the burner, the effect on work safety and health was also significant.

This invention has extremely great practical effects in terms of product quality, stable production, improved furnace productivity, and work safety.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the automatic control of the present invention. FIG. 2 shows a flowchart of the control system of the present invention. FIG. 3 is a sectional elevational view of a melting furnace to which the automatic control device of the present invention is applied. FIG. 4 is a diagram of the control of a conventional melting furnace. FIG. 5 is a control diagram of the same conventional melting furnace. FIG. 6 is a diagram showing an example of the circumferential arrangement of burner groups in the A zone, B zone, and C zone of the melting furnace. Figure 6

Claims (1)

[Scope of Claims] 1. A combustion state monitoring device, means for transmitting a video signal generated by the device, a device for electrically pattern-recognizing the signal and converting it into a signal, and converting the converted signal into a signal based on the combustion pressure of the burner. An automatically controlled melting furnace configured to have a means for transmitting feedback to a control device and a burner combustion pressure control device in series, and to automatically control combustion in the furnace by the device. 2. The automatically controlled melting furnace according to claim 1, wherein the means for transmitting the video signal generated by the combustion state monitoring device is an optical fiber. 3. In a melting furnace in which a tiltable melt holding furnace is installed outside the melting furnace, the holding furnace tilting angle detection device, the tilting angle and the increase/decrease trend signal of the tilting angle are detected by the burner combustion pressure control device. and a burner combustion pressure control device are connected in series, and the combustion in the melting furnace is automatically controlled by the connection device based on the amount of hot water in the holding furnace and the tendency of increase or decrease in the amount of hot water. The automatically controlled melting furnace according to claim 1, comprising: 4. A device for sampling the combustion atmosphere, a device for automatically analyzing the gas, and a device for automatically adjusting the fuel-air ratio based on the signal of the amount of reducing gas in the gas are installed in series, and the combustion atmosphere is reduced by the connected device. 4. The automatically controlled melting furnace according to claim 1, wherein the melting furnace is configured to automatically adjust the temperature.