JPS63273780A - Method of collecting dust in arc furnace for steel manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dust collection method for an arc furnace for steelmaking, and in particular to a method for collecting dust in an arc furnace for steelmaking, and in particular a method for inhaling molten gas generated when scrap, reduced iron, etc. are directly melted by arc heat. It concerns a method of collecting dust.

[Prior Art] It is well known that arc furnaces for steelmaking generally melt and refine scrap, reduced iron, and the like directly by the heat of the arc.

When the scrap, reduced iron, etc. are melted, dissolved gas is generated, and this dissolved gas contains a large amount of dust. Therefore, a dust collection method using a device as shown in FIG. 2 has been conventionally adopted. As shown in the figure, a steelmaking arc furnace a is provided within an enclosure. The lid C of this arc furnace a has a first blower d and a '1st bag house e.
were connected by piping in order. Further, a duct g is provided on the ceiling f of the enclosure, to which a second blower and a second bag house 1 are sequentially connected via piping. Adopting such a device, it is one of the conventional arc furnaces for steelmaking! The dust removal method was as follows.

The dissolved gas generated in the arc furnace a is controlled by controlling the air volume of the first blower d to maintain the furnace internal pressure at a constant negative pressure, or by controlling the flow rate of the first blower d according to a certain program.
The dust was collected directly from inside the furnace by controlling the time.

In addition, the dissolved gas leaking from the arc furnace a and staying in the enclosure can be contained by controlling the air volume of the second blower to a constant level, or by controlling the air volume of the second blower by manual operation. Dust was collected indirectly by inhaling the dissolved gas leaking from the arc furnace a.

[Problems to be Solved by the Invention] By the way, in this type of dust collection method for steelmaking arc furnaces, there are the following problems when dust is collected directly from inside the zero arc furnace a. In addition, the amount of dissolved gas varies greatly depending on the type of scrap input into the furnace, the progress of melting in the furnace, the use of burners in the furnace, the amount of oxygen sucked into the furnace, etc. When controlling the air volume of the first blower d using internal pressure or a program, there is a problem in that the amount of ffl is too large or too small, and that it is not possible to take adequate measures.

On the other hand, when the dissolved gas leaked from the arc furnace a is inhaled and dust is collected indirectly, controlling the air volume of the second blower to a constant value will result in excessive or insufficient air volume, and the second blower may be manually operated. However, there was a problem in that controlling the blower required manual labor and making accurate control difficult.

In view of the above-mentioned problems, the present invention has been developed to improve the thermal efficiency of an arc furnace by collecting dust appropriately according to the amount of dissolved gas generated, and to achieve energy saving. The object of the present invention is to provide a dust collection method for an arc furnace.

[Means for Solving the Problems] In order to solve the problems in the prior art, the present invention provides a method for directly inhaling the molten gas generated in the arc furnace from inside the furnace when melting scrap, reduced iron, etc. On the other hand, the dissolved gas leaked from the furnace is collected by indirectly inhaling the dissolved gas, the rising air temperature of this leaked dissolved gas is detected, and depending on the detected temperature, the dissolved gas is directly sucked from inside the furnace. It is designed to control the amount of gas inhaled.

[Function] Made as described above, the molten gas generated in the arc furnace is directly sucked in from inside the furnace and collected, while the molten gas leaked from the furnace is indirectly sucked in and collected. By detecting the temperature of the rising airflow of dissolved gas leaked from the furnace, the amount of dissolved gas directly sucked from inside the furnace is determined.
Utilizing the phenomenon that if the amount of dissolved gas increases, the temperature of the rising airflow of dissolved gas leaking from the furnace rises, if that temperature rises, the amount of dissolved gas sucked directly from inside the furnace is increased, and the temperature increases. When the amount of dissolved gas is lowered, the amount of dissolved gas sucked directly from inside the furnace is controlled to be reduced, thereby achieving optimal dust collection.

[Example] An example of the dust collection method for a steelmaking arc furnace of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the configuration of an apparatus employed to carry out the method of the present invention. As shown in the figure, a steelmaking arc furnace 1 is provided inside an enclosure 2. A first blower 4 and a first bag house 5 are installed in the lid 3 of the arc furnace 1 through the enclosure 2 to directly suck in dissolved gas generated in the furnace and collect dust. Piping is connected in order. Further, a duct 7 is provided in the ceiling 6 of the enclosure 2 and is opened to face the dissolved gas leaking from the arc furnace 1. This duct 7 is connected in sequence to a second blower 8 and a second bag house 9 in order to indirectly suck in dissolved gas leaked from the arc furnace 1 and collect dust. Furthermore, a first temperature sensor 1o is provided on the ceiling 6 of the enclosure 2 directly above the arc furnace 1. A first control system 11 is connected to this first temperature sensor 10, and is connected to the first feeder FF1 4 via a first arithmetic unit 12 and a first rotation speed control device 13 in order. There is. Furthermore,
A second temperature sensor 14 is provided on the ceiling 6 of the enclosure 2 at a position that does not directly receive the rising airflow of dissolved gas leaking from the arc furnace 1.

A second control system 15 is connected to the second temperature hinger 14, which is connected to the second blower 8 via a second arithmetic unit 16 and a second rotational speed control device 17 in this order. .

Note that, for example, a thermal lightning pair is used for the M7 and the second temperature sensors 10, 14, and the first and second arithmetic units 1t1
For example, a microcomputer is used for 2.16, and an electrical or mechanical rotation speed control device is used for the first and second rotation speed control devices 13.17.

Next, an embodiment of the method of the present invention will be described based on the above-mentioned apparatus example.

Scrap, reduced iron, etc. introduced into the steelmaking arc furnace 1 are directly melted by arc heat. As melting progresses, melted gas fills the furnace and begins to leak out of the furnace. Ceiling 6 of enclosure 2 that directly receives the rising airflow of this leaked dissolved gas
A first temperature sensor 10 is provided at , and this first temperature sensor 10 detects the temperature of the rising airflow of dissolved gas and transmits the detected value to the first arithmetic unit 12 .

The first computing device 12 receives the signal and uses the phenomenon that as the amount of dissolved gas increases, the temperature of the rising airflow of dissolved gas leaking from the furnace increases, and the temperature rises above the target value. If the number of revolutions decreases, the number of revolutions is increased, and if the number of revolutions decreases, the number of revolutions is decreased.An appropriate number of revolutions is calculated according to the amount of dissolved gas, and the output is sent to the first number of revolutions control device 13. give. In response to this output, the first rotational speed control device 13 controls the air volume by setting the first blower 4 at an appropriate rotational speed according to the amount of dissolved gas generated from the furnace. That is, the dissolved gas is sucked in directly from inside the furnace at an appropriate air volume and transferred to the first bag house 5, thereby performing optimal dust collection.

On the other hand, as the amount of dissolved gas leaking from the arc furnace 1 and staying in the enclosure 2 increases, it affects the second temperature sensor 14, and its temperature is detected.

This second temperature sensor 14 detects the temperature of the dissolved gas remaining in the enclosure 2 and sends the detected value to a second arithmetic unit 16.
Send to. The second arithmetic unit 16 receives the signal and
When the amount of gas leaking from the furnace increases and the amount of gas remaining in the enclosure 2 increases, the atmospheric temperature inside the enclosure increases.Using this phenomenon, if the temperature rises above the target value, the rotation will start. An appropriate rotational speed is calculated according to the amount of retained gas, such that the rotational speed is increased and the rotational speed is decreased when the rotational speed is decreased, and the calculated rotational speed is given to the second rotational speed control device 17 as an output. In response to this output, the second rotational speed control device 17 controls the amount by setting the second feeding T@ machine 8 at an appropriate rotational speed according to the amount of gas retained in the enclosure. That is, the dissolved gas leaking from the furnace is sucked indirectly from within the enclosure 2 with an appropriate air volume and transferred to the second bag house 9, thereby performing optimal dust collection.

By performing optimal dust collection using this method, it is possible to reduce the ejection of flames and dust from the furnace body, and also to prevent excessive exhaust of dissolved gas and improve the thermal efficiency of the furnace. It is.

Further, since the rotational speed of the first and second blowers 4.8 is controlled according to the amount of generated dissolved gas, the power is reduced.

In this way, the thermal efficiency of the furnace is improved and the power of the first and second blowers 4.8 is reduced, so that energy saving is achieved.

In this example, not only direct dust collection from inside the furnace but also indirect dust collection from inside the enclosure 2 was controlled based on the relationship between the temperature of the dissolved gas leaked and the amount of dissolved gas. However, since what is important is the thermal efficiency of the steelmaking arc furnace 1, at least direct dust collection from inside the furnace should be controlled from this relationship.

In this embodiment, the rotation speeds of the first and second blowers 4 and 8 are controlled to adjust the air volume. The air volume may be controlled by interposing on-off valves (not shown) and adjusting the valve openings.

[Effects of the Invention] According to the present invention, the following excellent effects are achieved.

(1) The temperature of the rising airflow of dissolved gas leaking from the furnace is detected, and the amount of dissolved gas sucked directly from inside the furnace is controlled according to this detected temperature. By increasing the amount of gas inhaled, it is possible to reduce the ejection of flames and dust from the furnace body, and if the temperature decreases, the amount of dissolved gas inhaled can be reduced to prevent excessive exhaust of dissolved gas. By preventing this, the temperature inside the furnace can be maintained constant and the thermal efficiency of the furnace can be improved, and dust collection can be performed optimally according to the amount of generated dissolved gas.

(2) By controlling the intake amount of dissolved gas in this way, it is possible to reduce the power of the blower, etc. that controls the suction force, and as mentioned above, thermal efficiency is improved, so energy saving can be achieved. Can be done.

[Brief explanation of drawings]

FIG. 1 is a system diagram for explaining the dust collection method for a steelmaking arc furnace of the present invention, and FIG. 2 is a system diagram for explaining the conventional method. In the figure, 1 is a steelmaking arc furnace, 2 is an enclosure, 4 is a first blower II, 7 is a duct, 8 is a second blower, and 10 is a first blower.
11 is a first control system, 12 is a first calculation device, and 13 is a first rotation speed control device. Patent applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Representative patent attorney: Nobuo Kinutani Figure 1 Figure 2

Claims (1)

[Claims] When melting scrap, reduced iron, etc., the molten gas generated in the arc furnace is sucked directly from inside the furnace and collected, while the molten gas leaking from the furnace is sucked indirectly through the enclosure that covers the arc furnace. Dust collection for an arc furnace for steelmaking, in which the rising air temperature of the leaked molten gas is detected, and the amount of molten gas sucked directly from the furnace is controlled according to the detected temperature. Method.